Difference in antigen presentation pathways between cortical and medullary thymic epithelial cells

Antigen presentation by thymic epithelial cells (TEC) to T cells that undergo maturation is one of the major events in the selection of the T cell repertoire. We have already reported that medullary TEC lines (mTEC) established from newborn C57BL/6 (H-2b) mice are able to present a soluble antigen, ovalbumin (OVA), to OVA-specific, I-Ab restricted helper T cell lines but cortical TEC (cTEC) lines are not (Mizuochi, T. et al., J. Exp. Med. 1992. 175: 1601). In this report, to clarify the cause of this difference, we analyzed the biochemical nature as well as the distribution of both major histocompatibility complex (MHC) class II molecules and invariant chains (Ii) in both TEC by immunoprecipitation and laser confocal scanning microscopic analysis, as well as the expression of mRNA encoding H-2Ma or H-2Mb. Our results demonstrate that cTEC and mTEC are both able to present peptide antigens to peptide-specific, I-Ab-restricted helper T cell hybridoma and are able to present class II MHC alloantigens to an I-Ab-specific T cell line, that mRNA for H-2Ma and H-2Mb are expressed in both TEC, that cTEC and mTEC apparently incorporate tetramethylrhodamine isothiocyanate-labeled OVA in the same manner, and that the SDS-stable MHC class II molecules, onto which peptides were loaded, are formed in both cTEC and mTEC. However, these molecules were more rapidly degraded in mTEC than in cTEC. In addition, two Ii-derived polypeptides of approximately 21 kDa and 10 kDa were precipitated by the anti-class II monoclonal antibody Y3P; 10-kDa polypeptides were detected in the both TEC, while 21-kDa polypeptides were detected only in cTEC. Finally, beta chains of MHC class II with less sialylated oligosaccharides were precipitated from the cell surface of cTEC. Taken together, these results suggest that there are substantial differences in the antigen-presenting pathways of cTEC and mTEC, and these difference might be responsible for T cell selection events in the thymus.     

Total spinal anesthesia after posterior lumbar plexus block

We report a case of total spinal anaesthesia which occurred after a lumbar plexus block using a posterior approach. After total hip arthroplasty under general anaesthesia, a lumbar plexus block was performed according to Winnie's landmarks at the L4 interspace using a nerve stimulator. Aspiration test for blood and spinal fluid were both negative, as well as a test dose of 3 mL lidocaine 2%-bupivacaine 0.5%. One minute after the injection of 27 mL of the same mixture, a complete anaesthetic block occurred with hypotension and loss of consciousness requiring intubation and controlled ventilation during 3h30, without sequelae. Lumbar plexus block using a posterior approach must be performed cautiously and a slow and fractionated injection of the full dose is recommended.     

Pulmonary and systemic fat embolization after medullary canal pressurization: a hemodynamic and histologic investigation in the dog

BACKGROUND: The potential to produce fat embolism may be important in determining the ideal method and timing of fracture treatment in patients with preexisting lung injury. METHODS: Four dogs underwent femoral and tibial canal reaming and pressurization. Blood gas samples were analyzed, and pulmonary arterial pressure was monitored at 1 and 72 hours. Animals were killed 72 hours postoperatively, and the lungs, kidneys, and brain were examined histologically and compared with equivalent specimens from four control dogs that had not undergone femoral and tibial canal reaming and pressurization. RESULTS: Postmortem, intravascular fat persisted for 72 hours after induction of pulmonary fat embolism. Mean PaO2 was unchanged from baseline at 72 hours after canal pressurization. Canal pressurization caused a sustained increase in pulmonary arterial pressure (p=0.02) for 1 hour after canal pressurization. The mean pulmonary edema score at 72 hours was 29+/-3. Only a scant polymorph infiltrate (zero to two polymorphs per high-power field) was present at any time. No hyaline membranes were seen at any time. The percentage area occupied by intravascular fat in the lungs was 0.0214+/-0.0058 at 72 hours. No signs of ischemia or inflammation were seen in either the cerebral or the renal specimens. CONCLUSION: This study is the first to show that intravascular fat persists in the lungs, kidneys, and brain for 72 hours after canal pressurization and, by itself, does not cause pathologic evidence of acute inflammation.     

Functional morphology of the spinal canal after endplate, wedge, and burst fractures

The plasma-ion shower method is an effective technique for the SEM examination of un-coated electrically non-conductive specimens. However, milling damage to specimens cannot be prevented by the irradiation method using accelerated Ar ion beam. We, therefore, applied positive ions obtained by plasma discharge to the specimen like a shower by reflecting from the target electrode surface. He, N2 or Ar was used as the environmental gas, and the discharge voltage was varied from 200 V to 1000 V. At 5 kV to 25 kV of SEM accelerating voltage, it was possible to visualize un-coated hard and soft biological and inorganic specimens under 5 mA or 10 mA of discharge current and 5 min or 10 min of processing time.     

Hearing loss after spinal anesthesia. An audiological controlled trial

Audiological tests were conducted on 34 patients before and after undergoing an operation in spinal anaesthesia. One of these patients developed a considerable unilateral hearing loss in the low-frequency range, which persisted until an epidural blood-patch was given. Unexpectedly, we also found a general small but significant threshold shift at 500 Hz, which has never before been described in the literature. The biological mechanism is discussed, and the results suggest that the explanation of the hearing loss could be a condition similar to endolymphatic hydrops, resulting from perilymphatic hypotension due to loss of liquor during and after the spinal anaesthesia.     

The advantages of the lateral decubitus position after spinal anesthesia with hyperbaric tetracaine

Exercise-induced bronchoconstriction (EIB) is widely prevalent in asthmatic patients. Eosinophilic airway inflammation is considered to be a major factor in the pathogenesis of asthma. However, the effects of eosinophilic airway inflammation on EIB have been elucidated insufficiently. To examine the relationship between the severity of EIB and eosinophilic inflammation, sputum induction and exercise challenge were performed in 21 asthmatic patients. Significantly higher percentages of eosinophils and levels of eosinophil cationic protein (ECP) were found in induced sputum in EIB-positive asthmatics (median (range), eosinophils: 23.5 (11.0-61.0)%; ECP: 1,475 (74.8-17,701) ng x mL(-1)) than in EIB-negative asthmatics (eosinophils: 6.0 (1.0-41.5)% (p=0.006); ECP: 270.6 (10.8-7,700) ng x mL(-1) (p=0.049)). There was a significant correlation between the severity of EIB and the sputum eosinophil percentage (r=0.59, p=0.009) and the level of ECP (r=0.47, p=0.037). The area under the curve of the forced expiratory volume in one second for 30 min after exercise correlated with the percentage of eosinophils (r=0.60, p=0.008) and the level of ECP (r=0.45, p=0.04). There was no correlation between airway responsiveness to methacholine on the one hand and EIB, sputum eosinophils or ECP on the other. In conclusion, these results provide evidence that the severity of bronchoconstriction evoked by exercise is more closely related to eosinophilic airway inflammation than airway hyperresponsiveness to methacholine in asthmatic patients.     

Geometric changes in the cervical spinal canal during impact

SUMMARY OF BACKGROUND DATA: Although the extent of injury after cervical spine fracture can be visualized by imaging, the deformations that occur in the spinal canal during injury are unknown. STUDY DESIGN: This study compared spinal canal occlusion and axial length changes occurring during a simulated compressive burst fracture with the residual deformations after the injury. METHODS: Canal occlusion was measured from changes in pressure in a flexible tube with fluid flowing through it, placed in the canal space after removal of the cord in cadaver specimens. To measure canal axial length, cables were fixed in C1 and led through the foramen transversarium from C2-T1, then out through the base, where they were connected to the core rods of linearly variable differential transformers (LVDT). Axial compressive burst fractures were created in each of ten cadaveric cervical spine specimens using a drop-weight, while force, distraction, and occlusion were monitored throughout the injury event. Pre- and post-injury radiographs and computed tomography scans compared transient and post-injury spinal canal geometry changes. RESULTS: In all cases, severe compressive injuries were produced. Three had an extension component in addition to compression of the vertebra and retropulsion of bone into the canal. The mean post-injury axial height loss measured from radiographs was only 35% of that measured transiently (3.1 mm post-injury, compared with 8.9 mm measured transiently), indicating significant recovery of axial height after impact. Post-injury and transient height loss were not significantly correlated (r2 = 0.230, P = 0.16) demonstrating that it is not a good measure of the extent of injury. Similarly, mean post injury canal area was 139% of the minimum area measured during impact, indicating recovery of canal space, and post-injury and transient values were not significantly correlated (r2 = 0.272, P = 0.12). Mean post-injury midsagittal diameter was 269% of the minimum transient diameter and showed a weak but significant correlation (r2 = 0.481, P = 0.03). CONCLUSIONS: Two potential spinal cord injury-causing mechanisms in axial bursting injuries of the cervical spine are occlusion and shortening of the canal. Post-injury radiographic measurements significantly underestimate the actual transient injury that occurs during impact.     

Ultrastructure of the glial cells after spinal cord compression in rabbits

Sump syndrome is a rare complication of biliary-enteric anastomosis. Classically, the distal bile duct becomes obstructed by gastrointestinal debris after choledochoduodenostomy, resulting in cholangitis or, less commonly pancreatitis. Obstruction of the biliary tree by gastrointestinal contents after Roux-en-Y choledochojejunostomy or hepaticojejunostomy has not been described in the English-language literature. This report details the diagnostic and operative management of the first patient with sump syndrome after hepaticojejunostomy. The presumed pathophysiology was reflux of vegetable matter up the efferent limb, resulting in hepatic duct obstruction and cholangitis. The patient ultimately required complex choledochoscopic drainage of the intrahepatic biliary tree and revision of the previous Roux-en-Y hepaticojejunostomy.     

Presence of atrial natriuretic peptide in rat thyroid medullary carcinoma cell line

In 1923, Masson described a neoplastic process consisting of papillary hyperplasia of the endothelial cells, with a consequent obliteration of the vascular lumen, followed later by degenerative changes. Masson coined the term vegetant intravascular haemangioendothelioma, however, these days it is more commonly known as papillary endothelial hyperplasia (PEH), or by the pseudonym, Masson's tumour. Although relatively rare, there are numerous accounts of PEH in the literature, describing its predilection for the head and neck region. Our case report describes the finding of a PEH within the paranasal sinuses, a site not previously mentioned even in the largest of series found on literature search. We will then discuss the relevant histological features of the lesion, and its natural history.     

Morphogenesis of the spinal canal, normal and stenotic

The closest formative developmental dependence of the axial skeleton upon the morphogenesis of the intraspinal nervous structures is reflected in the roentgen features of the individual vertebrae as well as of the vertebral column in its entirety. The vertebroneural developmental events are characterized by a steady relative decrease in size of the nervous structures (the first to be laid down and huge in the embryonic period) under a corresponding increase in size of the skeletogenic tissues. There exists experimental evidence that the maintenance of the necessary developmental balance between the two tissues, the bony and the skeletogenic, is a function of the nervous substance. The tight spinal canal appears to result from a failure of the latter neural function leading to overgrowth of the bony structures, viz., to massive vertebrae and laminae encroaching upon the neural contents. Morphogenesis of the normal and tight lumbar spinal canal is discussed with special reference to the developmental interrelations between the cauda equina complex and the lumbar vertebrae.     

Migration of bullet in the spinal canal: a case report

As the spinal canal expands at T10 level naturally, it has been thought that the migration of a bullet within the spinal canal above this level is prevented and the migration of a bullet may only occur between T10 and S1 level. Here, a very rare case of a bullet traversing the length of the spinal canal is reported.     

羊膜上皮细胞移植对大鼠脊髓半横断损伤后神经再生的促进作用

目的:探讨羊膜上皮细胞(AECs)移植对大鼠脊髓半横断损伤后神经再生的影响,为AECs移植修复脊髓损伤(SCI)提供实验依据.方法:采用30只Wistar大鼠建立脊髓半横断损伤模型.损伤后分别进行明胶海绵加生理盐水移植(明胶海绵组)和明胶海绵加AECs移植(AECs移植组),同时设SCI模型组和假手术组作为对照.移植后2和4周,常规组织学方法观察移植物和脊髓组织结构;采用免疫荧光组织化学技术观察移植物和脊髓组织中神经丝蛋白(NF)阳性神经纤维、5-羟色胺(5-HT)能神经纤维、降钙素基因相关肽(CGRP)能神经纤维及神经胶质酸性蛋白(GFAP)阳性细胞.采用荧光红顺行示踪技术观察移植后脊髓神经纤维恢复情况;BBB功能评分方法评价移植后大鼠后肢运动功能恢复情况.结果:AECs移植可促进脊髓本身神经纤维的再生,并促进了NF、5-HT和CGRP神经纤维的再生,再生的神经纤维可穿过GFAP阳性区域进入移植物中,AECs移植组移植物中NF阳性神经纤维数明显多于明胶海绵组(P<0.05).AECs移植组、明胶海绵组及SCI模型组BBB评分与假手术组比较差异有统计学意义(P<0.05),而AECs移植组与明胶海绵组和SCI模型组BBB评分比较差异无统计学意义(P>0.05).结论:AECs移植可促进SCI后神经纤维的再生.     

Apoptosis of human intestinal epithelial cells after bacterial invasion

Epithelial cells that line the human intestinal mucosa are the initial site of host invasion by bacterial pathogens. The studies herein define apoptosis as a new category of intestinal epithelial cell response to bacterial infection. Human colon epithelial cells are shown to undergo apoptosis following infection with invasive enteric pathogens, such as Salmonella or enteroinvasive Escherichia coli. In contrast to the rapid onset of apoptosis seen after bacterial infection of mouse monocyte-macrophage cell lines, the commitment of human intestinal epithelial cell lines to undergo apoptosis is delayed for at least 6 h after bacterial infection, requires bacterial entry and replication, and the ensuing phenotypic expression of apoptosis is delayed for 12-18 h after bacterial entry. TNF-alpha and nitric oxide, which are produced as components of the intestinal epithelial cell proinflammatory program in the early period after bacterial invasion, play an important role in the later induction and regulation of the epithelial cell apoptotic program. Apoptosis in response to bacterial infection may function to delete infected and damaged epithelial cells and restore epithelial cell growth regulation and epithelial integrity that are altered during the course of enteric infection. The delay in onset of epithelial cell apoptosis after bacterial infection may be important both to the host and the invading pathogen since it provides sufficient time for epithelial cells to generate signals important for the activation of mucosal inflammation and concurrently allows invading bacteria time to adapt to the intracellular environment before invading deeper mucosal layers.     

Biphasic modulation of spinal nociceptive transmission from the medullary raphe nuclei in the rat

The modulatory effects of electrical and chemical (glutamate) stimulation in the rostral ventromedial medulla (RVM) on spinal nociceptive transmission and a spinal nociceptive reflex were studied in rats. Electrical stimulation at a total 86 sites in the RVM in the medial raphe nuclei (n = 54) and adjacent gigantocellular areas (n = 32) produced biphasic (facilitatory and inhibitory, n = 43) or only inhibitory (n = 43) modulation of the tail-flick (TF) reflex. At these 43 biphasic sites in the RVM, facilitation of the TF reflex was produced at low intensities of stimulation (5-25 microA) and inhibition was produced at greater intensities of stimulation (50-200 microA). At 43 sites in the RVM, electrical stimulation only produced intensity-dependent inhibition of the TF reflex. Activation of cell bodies in the RVM by glutamate microinjection reproduced the biphasic modulatory effects of electrical stimulation. At biphasic sites previously characterized by electrical stimulation, glutamate at a low concentration (5 nmol) produced facilitation of the TF reflex; a greater concentration (50 nmol) only inhibited the TF reflex. In electrophysiological experiments, electrical stimulation at 62 sites in the RVM produced biphasic (n = 26), only inhibitory (n = 26), or only facilitatory (n = 10) modulation of responses of lumbar spinal dorsal horn neurons to noxious cutaneous thermal (50 degrees C) or mechanical (75.9 g) stimulation. Facilitatory effects were produced at lesser intensities of stimulation and inhibitory effects were produced at greater intensities of stimulation. The apparent latencies to stimulation-produced facilitation and inhibition, determined with the use of a cumulative sum method and bin-by-bin analysis of spinal neuron responses to noxious thermal stimulation of the skin, were 231 and 90 ms, respectively. The spinal pathways conveying descending facilitatory and inhibitory influences were found to be different. Descending facilitatory influences on the TF reflex were conveyed in ventral/ventrolateral funiculi, whereas inhibitory influences were conveyed in dorsolateral funiculi. The results indicate that descending inhibitory and facilitatory influences can be simultaneously engaged throughout the RVM, including nucleus raphe magnus, and that such influences are conveyed in different spinal funiculi.     

Continuous spinal anesthesia vs. combined spinal-epidural anesthesia in emergency surgery. The combined spinal-epidural anesthesia technique does not offer an advantage of spinal anesthesia with a microcatheter

In this prospective study we investigated the efficacy of microcatheter spinal anaesthesia in comparison with a combined spinal-epidural technique in trauma patients. METHODS: After institutional approval 60 patients undergoing urgent lower-limb surgery randomly received either CSA (22 G Sprotte needle, 28 G nylon catheter) in group 1 or CSE (18 G Tuohy needle, 22 G epidural catheter and 25 G pencil-point needle) in group 2. An initial subarachnoid bolus of 2 ml of plain bupivacaine 0.5% was injected in both groups. Difficulties with the lumbar puncture or catheter insertion, the time required for performance of either technique and the onset of analgesia at T12 were documented. If analgesia did not reach T12 within 20 min, supplemental bupivacaine was injected either intrathecally or epidurally up to a maximum of 5 ml in the CSA group or 16 ml in the CSE group. RESULTS: The number of lumbar punctures (CSA: n = 1.8 +/- 1.5; CSE: n = 2.6 +/- 1.8; P = 0.05) and the incidence of technical problems (CSA: 13%, CSE: 47%; P = 0.012) was higher in the CSE group. In contrast to CSA, performance of CSE was more time consuming (CSA: 8 +/- 3 min, CSE: 15 +/- 8 min; P = 0.0003), and the total dose of local anaesthetics was higher in the CSE group (CSA: 3.2 +/- 1 ml, CSE: 9.7 +/- 5 ml; P < 0.0001). CONCLUSIONS: Because of the higher incidence of technical problems, more time was required for the performance of CSE. As a consequence, microcatheter CSA might be preferred over CSE in trauma patients.     

Changes in fluid filtration capacity and blood flow after tourniquet in knee operations with spinal anesthesia

In this randomized, multicenter, observer-blind study, the efficacy, safety and tolerability of amoxycillin/clavulanate and cefaclor were compared in children with a clinical diagnosis of acute otitis media. Patients aged between 1 and 12 years received either amoxycillin/clavulanate (250 mg/62 mg t.i.d., or 125 mg/31 mg t.i.d. if aged under 6 years) or cefaclor (250 mg t.i.d., or 125 mg t.i.d. if aged under 6 years) for 7 days. The amoxycillin/clavulanate regimen was based on a dose of 20/5 mg/kg/day (representing 20 mg amoxycillin plus 5 mg clavulanic acid) in three divided doses. Patients were followed-up at the end of therapy and on days 10-12 and 38-40. At the end of the study (days 38-40), clinical success rates were 91.4% for amoxycillin/clavulanate and 78.6% for cefaclor. The difference was statistically significant (p = 0.008). After the 7 days of treatment, 3 patients (2.9%) in the amoxycillin/clavulanate group had clinical failure, compared with 18 patients (16.1%) in the cefaclor group (p < 0.001). Both treatments were well tolerated and there were no statistically significant differences between the groups in adverse event profiles. The incidence of diarrhea was low (7.0% amoxycillin/clavulanate, 8.4% cefaclor) and was generally of mild or moderate intensity. The study demonstrated that amoxycillin/clavulanate was significantly more effective clinically than cefaclor in the treatment of acute otitis media in children.