Percutaneous Argon-Helium Cryoablation for Small Hepatocellular Carcinoma Located Adjacent to a Major Organ or Viscus: A Retrospective Study of 92 Patients at a Single Center.

BACKGROUND Cryoablation of hepatocellular carcinoma (HCC) close to major organs or viscus is challenging because it can cause complications. This retrospective study aimed to investigate the safety and efficacy of percutaneous argon-helium cryoablation of small HCC located adjacent to major organs or viscus. MATERIAL AND METHODS Ninety-two patients who underwent percutaneous argon-helium cryoablation between February 2012 and December 2018 at the Fifth Medical Center of the Chinese People's Liberation Army General Hospital were included. Treatment efficacy was evaluated by magnetic resonance imaging or triphasic computed tomography scan within 1 week after each cryoablation procedure. Local tumor progression, distant recurrence, and overall survival were analyzed using the Kaplan-Meier method and log-rank test. RESULTS A total of 92 patients with small HCC located adjacent to major organs or viscus who underwent cryoablation were retrospectively reviewed. The number of patients with tumors adjacent to the gallbladder, portal or hepatic vein, diaphragm, stomach, heart, and intestine was 22, 1, 39, 6, 8, and 16, respectively. Cumulative local tumor progression rates at 1 and 2 years were 2.8% and 7.3%, respectively. Cumulative distant recurrence rates at 1, 2, and 3 years were 11.1%, 17.6%, and 20.7%, respectively. The overall survival rates at 1, 2, and 4 years were 100%, 93.6%, and 74.9%, respectively. Major complications were observed in 5 (5.4%) patients. Minor complications were observed in 85 (92.4%) patients. CONCLUSIONS This experience from a single center showed that percutaneous argon-helium cryoablation was safe and effective in the management of small HCC that is located adjacent to major organs or viscus.

Argon treatment after experimental subarachnoid hemorrhage: evaluation of microglial activation and neuronal survival as a subanalysis of a randomized controlled animal trial.

Hereinafter, we evaluate argon's neuroprotective and immunomodulatory properties after experimental subarachnoid hemorrhage (SAH) examining various localizations (hippocampal and cortical regions) with respect to neuronal damage and microglial activation 6, 24 and 72 hours after SAH. One hour after SAH (endovascular perforation rat model) or sham surgery, a mixture of gas containing 50% argon (argon group) or 50% nitrogen (control group) was applied for 1 hour. At 6 hours after SAH, argon reduced neuronal damage in the hippocampal regions in the argon group compared to the control group (P < 0.034). Hippocampal microglial activation did not differ between the treatment groups over time. The basal cortical regions did not show a different lesion pattern, but microglial activation was significantly reduced in the argon group 72 hours after SAH (P = 0.034 vs. control group). Whereas callosal microglial activation was significantly reduced at 24 hours in the argon-treated group (P = 0.018). Argon treatment ameliorated only early hippocampal neuronal damage after SAH. Inhibition of microglial activation was seen in some areas later on. Thus, argon may influence the microglial inflammatory response and neuronal survival after SAH; however, due to low sample sizes the interpretation of our results is limited. The study protocol was approved by the Government Agency for Animal Use and Protection (Protocol number: TVA 10416G1; initially approved by the "Landesamt für Natur, Umwelt und Verbraucherschutz NRW," Recklinghausen, Germany, on April 28, 2009).

Argon Mitigates Impaired Wound Healing Process and Enhances Wound Healing In Vitro and In Vivo.

Diabetic foot ulcers are associated with significant morbidity and mortality, and current treatments are far from optimal. Chronic wounds in diabetes are characterised by impaired angiogenesis, leukocyte function, fibroblast proliferation, and keratinocyte migration and proliferation. Methods: We tested the effect of exposure to argon gas on endothelial cell, fibroblast, macrophage and keratinocyte cell cultures in vitro and in vivo of a streptozotocin-induced diabetic mouse model. Results: Exposure to normobaric argon gas promotes multiple steps of the wound healing process. Argon accelerated angiogenesis, associated with upregulation of pro-angiogenic Angiopoietin-1 and vascular endothelial growth factor (VEGF) signalling in vitro and in vivo. Treatment with argon enhanced expression of transforming growth factor (TGF)-ß, early recruitment of macrophages and keratinocyte proliferation. Argon had a pro-survival effect, inducing expression of cytoprotective mediators B-cell lymphoma 2 and heme oxygenase 1. Argon was able to accelerate wound closure in a diabetic mouse model. Conclusion: Together these findings indicate that argon gas may be a promising candidate for clinical use in treatment of diabetic ulcers.

Argon preconditioning enhances postischaemic cardiac functional recovery following cardioplegic arrest and global cold ischaemia.

OBJECTIVES: Previous studies demonstrated that preconditioning with argon gas provided a marked reduction in inflammation and apoptosis and increased myocardial contractility in the setting of acute myocardial ischaemia-reperfusion (IR). There is substantial evidence that myocardial IR injury following cardioplegic arrest is associated with the enhancement of apoptosis and inflammation, which is considered to play a role in cardiac functional impairment. Therefore, the present study was designed to clarify whether preconditioning with argon gas enhances recovery of cardiac function following cardioplegic arrest. METHODS: Sprague-Dawley rats were anaesthetized and ventilated and allocated to (i) the control group (control IR, n = 10) and (ii) the in vivo group (argon IR), which received 3 cycles of argon (50% argon, 21% oxygen and 29% nitrogen, n = 10) administered for 5 min interspersed with 5 min of a gas mixture (79% nitrogen and 21% oxygen). The hearts were excised and then evaluated in an erythrocyte-perfused isolated working heart system. Cold ischaemia (4°C) for 60 min was induced by histidine-tryptophan-ketoglutarate cardioplegia, followed by 40 min of reperfusion. Cardiac functional parameters were assessed. In left ventricular tissue samples, the expressions of extracellular-regulated kinase (ERK1/2), AKT serine/threonine kinase (Akt), jun N-terminal kinase (JNK), endothelial nitric oxide synthase (eNOS) and HMGB1: high-mobility group box 1 (HMGB1) protein were assessed by western blot, and high-energy phosphates were evaluated by high-performance liquid chromatography. RESULTS: At the end of reperfusion, the rats preconditioned with argon showed significantly enhanced recovery of cardiac output (101 ± 6% vs 87 ± 11%; P < 0.01), stroke volume (94 ± 4% vs 80 ± 11%; P = 0.001), external heart work (100 ± 6% vs 81 ± 13%; P < 0.001) and coronary flow (90 ± 13% vs 125 ± 21%; P < 0.01) compared with the control IR group. These results were accompanied by a significant increase in the levels of myocardial phosphocreatine (23.71 ± 2.07 µmol/g protein vs the control IR group, 13.50 ± 4.75; P = 0.001) and maintained adenosine triphosphate levels (13.62 ±1.89 µmol/g protein vs control IR group adenosine triphosphate: 10.08 ± 1.94 µmol/g; P = 0.017). Additionally, preconditioning with argon markedly reduced the activation of JNK (0.11 ± 0.01 vs 0.25 ± 0.03; P = 0.005) and the expression of HMGB1 protein (0.52 ± 0.04 vs 1.5 ± 0.10; P < 0.001) following reperfusion. CONCLUSIONS: Preconditioning with argon enhanced cardiac functional recovery in rat hearts arrested with histidine-tryptophan-ketoglutarate cardioplegia, thereby representing a potential novel cardioprotective approach in cardiac surgery.

Argon attenuates multiorgan failure following experimental aortic cross-clamping.

AIMS: Argon has been shown to prevent ischaemic injuries in several scenarios of regional ischaemia. We determined whether it could provide a systemic effect in a model of multiorgan failure (MOF) induced by aortic cross-clamping. METHODS: Anaesthetized rabbits were submitted to aortic cross-clamping (30 min) and subsequent reperfusion (300 min). They were either ventilated with oxygen-enriched air throughout the protocol [fraction of inspired oxygen (FiO2 ) = 30%; control group) or with a mixture of 30% oxygen and 70% argon (argon groups). In a first group treated with argon ('Argon-Total'), its administration was started 30 min before ischaemia and maintained throughout the protocol. In the two other groups, the administration was started either 30 min before ischaemia ('Argon-Pre') or at the onset of reperfusion ('Argon-Post'), for a total duration of 2 h. Cardiovascular, renal and inflammatory endpoints were assessed throughout protocol. RESULTS: Compared with control, shock was significantly attenuated in Argon-Total and Argon-Pre but not Argon-Post groups (e.g. cardiac output = 62±5 vs. 29 ± 5 ml min-1 kg-1 in Argon-Total and control groups at the end of the follow-up). Shock and renal failure were reduced in all argon vs. control groups. Histopathological examination of the gut showed attenuation of ischaemic lesions in all argon vs. control groups. Blood transcription levels of interleukin (IL) 1ß, IL-8, IL-10 and hypoxia-inducible factor 1α were not significantly different between groups. CONCLUSION: Argon attenuated clinical and biological modifications of cardiovascular, renal and intestinal systems, but not the inflammatory response, after aortic cross-clamping. The window of administration was crucial to optimize organ protection.

The administration of argon during ex vivo normothermic perfusion in an experimental model of kidney ischemia-reperfusion injury.

BACKGROUND: Argon has shown potential as an organoprotective agent in numerous models of ischemia-reperfusion injury (IRI). The aim of this study was to evaluate the effects of argon gas during ex vivo normothermic perfusion (EVNP) in an experimental porcine model of kidney IRI. MATERIALS AND METHODS: After a warm ischemia time of 15 min and 17 h of static cold storage, porcine kidneys underwent 1 h of EVNP using leukocyte-depleted blood. During EVNP, kidneys were perfused with a gas composition either of 70% argon (n = 6), 70% nitrogen control (n = 6), or standard 95% oxygen (n = 6) balanced with 5% carbon dioxide. After EVNP, kidneys were reperfused with whole blood under standard conditions for 3 h to assess renal function and injury. RESULTS: During 1-h EVNP, the mean renal blood flow was numerically higher in the argon group (49.2 ± 16.2 mL/min/100 g; P = 0.320) compared with the nitrogen and oxygen groups (42.9 ± 18.64 and 37.71 ± 7.0 mL/min/100 g, respectively). Other measures of renal function and hemodynamics were not significantly different between the argon and control groups during this period. During reperfusion, no significant differences were found in functional parameters or inflammatory markers (P < 0.05). Histologic analysis revealed no significant change in morphology or hypoxia-inducible factor-1 alpha staining between gaseous groups. Nuclear hypoxia-inducible factor-1 alpha staining was observed only after 3 h of reperfusion. CONCLUSIONS: Our findings suggest that using 70% argon during 1 h of EVNP does not mediate a measurable organoprotective effect in an experimental porcine model of IRI.

Recurrent acute angle-closure attack due to plateau iris syndrome after cataract extraction with or without argon laser peripheral iridoplasty: a case report.

BACKGROUND: We describe two cases of recurrent acute angle-closure attack in patients with plateau iris syndrome after cataract extraction. Argon laser peripheral iridoplasty and cataract extraction have been used to reduce the occurrence of acute angle-closure attack in plateau iris syndrome although the risk cannot be completely eliminated. There is no consensus on the long term management of plateau iris syndrome. This is, as far as we know, the first case report of recurrent acute angle-closure attack in plateau iris syndrome after cataract extraction. CASE PRESENTATION: We report two cases of recurrent acute angle-closure attack in 2 Chinese patients with plateau iris syndrome. The first patient was a 69 year-old woman who received bilateral argon laser peripheral iridoplasty and cataract extraction 2 years prior to the latest acute angle-closure with right eye intraocular pressure 48 mmHg. The attack was aborted medically. Peripheral iridotomy was patent and argon laser peripheral iridoplasty marks were mostly at peripheral 2/3 of the iris. Anterior segment optical coherence tomography confirmed bilateral plateau iris configuration. Use of long term pilocarpine or repeated argon laser peripheral iridoplasty to prevent recurrent angle-closure attack was discussed but she opted for observation. The second patient was a 64 year-old man presented with acute angle-closure after cataract extraction despite placement of laser peripheral iridotomy. Plateau iris syndrome was confirmed by anterior segment optical coherence tomography and he received argon laser peripheral iridoplasty. CONCLUSIONS: Acute angle-closure due to plateau iris syndrome can still occur despite previous cataract extraction and argon laser peripheral iridoplasty. These are the first reported cases of recurrent acute angle-closure attack due to plateau iris syndrome following cataract extraction, with or without previous argon laser peripheral iridoplasty. Repeated treatment with argon laser peripheral iridoplasty or pilocarpine could be considered although the long term efficacy is questionable. Argon laser peripheral iridoplasty should be applied as peripheral as possible so as to open up the drainage angle effectively.

Argon inhalation attenuates retinal apoptosis after ischemia/reperfusion injury in a time- and dose-dependent manner in rats.

PURPOSE: Retinal ischemia and reperfusion injuries (IRI) permanently affect neuronal tissue and function by apoptosis and inflammation due to the limited regenerative potential of neurons. Recently, evidence emerged that the noble gas Argon exerts protective properties, while lacking any detrimental or adverse effects. We hypothesized that Argon inhalation after IRI would exert antiapoptotic effects in the retina, thereby protecting retinal ganglion cells (RGC) of the rat's eye. METHODS: IRI was performed on the left eyes of rats (n = 8) with or without inhaled Argon postconditioning (25, 50 and 75 Vol%) for 1 hour immediately or delayed after ischemia (i.e. 1.5 and 3 hours). Retinal tissue was harvested after 24 hours to analyze mRNA and protein expression of Bcl-2, Bax and Caspase-3, NF-κB. Densities of fluorogold-prelabeled RGCs were analyzed 7 days after injury in whole-mounts. Histological tissue samples were prepared for immunohistochemistry and blood was analyzed regarding systemic effects of Argon or IRI. Statistics were performed using One-Way ANOVA. RESULTS: IRI induced RGC loss was reduced by Argon 75 Vol% inhalation and was dose-dependently attenuated by lower concentrations, or by delayed Argon inhalation (1504±300 vs. 2761±257; p<0.001). Moreover, Argon inhibited Bax and Bcl-2 mRNA expression significantly (Bax: 1.64±0.30 vs. 0.78±0.29 and Bcl-2: 2.07±0.29 vs. 0.99±0.22; both p<0.01), as well as caspase-3 cleavage (1.91±0.46 vs. 1.05±0.36; p<0.001). Expression of NF-κB was attenuated significantly. Immunohistochemistry revealed an affection of Müller cells and astrocytes. In addition, IRI induced leukocytosis was reduced significantly after Argon inhalation at 75 Vol%. CONCLUSION: Immediate and delayed Argon postconditioning protects IRI induced apoptotic loss of RGC in a time- and dose-dependent manner, possibly mediated by the inhibition of NF-κB. Further studies need to evaluate Argon's possible role as a therapeutic option.

Dose dependent neuroprotection of the noble gas argon after cardiac arrest in rats is not mediated by K(ATP)-channel opening.

PURPOSE: Argon at a dosage of 70% is neuroprotective when given 1 h after cardiac arrest (CA) in rats. In a rodent model, we investigated if the neuroprotective effects of argon are dose dependent and mediated by adenosine triphosphate dependent potassium (K(ATP)) channels. METHODS: Forty-seven male Sprague-Dawley rats were subjected to 7 min of CA and 3 min of cardiopulmonary resuscitation (CPR). In protocol I animals were randomized to receive either 70% or 40% argon ventilation 1 h after successful CPR or no argon-treatment. Animals of the second protocol also received 1 h of 70% argon ventilation or no argon treatment but were randomized to a group receiving the K(ATP) channel blocker 5-hydroxydecanoate (5-HD). For all animals a neurological deficit score (NDS) was calculated daily for seven days following the experiment before the animals were killed and the brains harvested for histopathological analyses. RESULTS: All animals survived. Control animals exhibited severe neurologic dysfunction at all points in time as measured with the NDS. Argon treated animals showed significant improvements in the NDS through all postoperative days in a dose dependent fashion. This was paralleled by a significant reduction in the neuronal damage index in the neocortex and the hippocampal CA 3/4 region. Administration of 5-HD neither abolished the positive effects on functional recovery nor on histopathologic changes observed in the argon group. CONCLUSION: Our study demonstrates a dose dependent neuroprotective effect of argon administration in this rodent model, which is not mediated via ATP dependent potassium channels.

Modulation by the noble gas argon of the catalytic and thrombolytic efficiency of tissue plasminogen activator.

Argon has been shown to provide cortical as well as, under certain conditions, subcortical neuroprotection in all models so far (middle cerebral artery occlusion, trauma, neonatal asphyxia, etc.). This has led to the suggestion that argon could be a cost-efficient alternative to xenon, a metabolically inert gas thought to be gold standard in gas pharmacology but whose clinical development suffers its little availability and excessive cost of production. However, whether argon interacts with the thrombolytic agent tissue plasminogen activator, which is the only approved therapy of acute ischemic stroke to date, still remains unknown. This latter point is not trivial since previous data have clearly demonstrated the inhibiting effect of xenon on tPA enzymatic and thrombolytic efficiency and the critical importance of the time at which xenon is administered, during or after ischemia, in order not to block thrombolysis and to obtain neuroprotection. Here, we investigated the effect of argon on tPA enzymatic and thrombolytic efficiency using in vitro methods shown to provide reliable prediction of the in vivo effects of both oxygen and the noble inert gases on tPA-induced thrombolysis. We found that argon has a concentration-dependent dual effect on tPA enzymatic and thrombolytic efficiency. Low and high concentrations of argon of 25 and 75 vol% respectively block and increase tPA enzymatic and thrombolytic efficiency. The possible use of argon at low and high concentrations in the treatment of acute ischemic stroke if given during ischemia or after tPA-induced reperfusion is discussed as regards to its neuroprotectant action and its inhibiting and facilitating effects on tPA-induced thrombolysis. The mechanisms of argon-tPA interactions are also discussed.

Decompression sickness risk at 6553 m breathing two gas mixtures.

INTRODUCTION: The risk of severe decompression sickness (DCS) increases rapidly above 6248 m (20,500 ft) and is greater when breathing higher proportions of inert gas. Contemporary aircrew may be exposed to higher cabin altitudes while breathing molecular sieve oxygen concentrator (MSOC) product gas containing variable concentrations of oxygen, nitrogen, and argon. This study assessed the risk of DCS at 6553 m (21,500 ft) breathing two simulated MSOC product gas mixtures. METHODS: In a hypobaric chamber, 10 subjects each undertook 2 4-h exposures at 6553 m breathing either 75% O2:21% N2:4% Ar or 56% 02:42% N2:2% Ar. Subjects undertook regular activities simulating in-flight movements of fast jet aircrew. Venous gas emboli (VGE) "bubble" load was graded every 15 min using 2D and Doppler echocardiography by experienced operators blinded to breathing gas composition. RESULTS: DCS occurred in five exposures (25%), the earliest after less than 90 min at altitude. All were minor, single-site, uncomplicated limb bends that resolved with recompression. VGE occurred in 85% of exposures with some early-onset, heavy loads. Survival (Probit) analysis indicated that breathing 56% oxygen significantly decreased VGE latency relative to breathing 75% oxygen (relative potency 3.05). CONCLUSIONS: From 20 experimental exposures, the risk of DCS at 6553 m is estimated at 5% by 90 min and 20% at 3 h. Exploiting the negative predictive value of VGE latency as a surrogate measure of protection from DCS, at high cabin altitudes better MSOC performance (higher product gas oxygen concentrations) will protect more aircrew for longer.

Acute recovery of pneumoperitoneum using argon gas.

BACKGROUND AND PURPOSE: The argon-beam coagulator (ABC) is widely used in laparoscopic surgery as a method of electrocoagulation. Argon gas possesses properties that make it suitable as an alternative for establishing pneumoperitoneum. We present a case in which an ABC was used to deliver argon gas urgently in order to salvage an acutely compromised pneumoperitoneum. METHODS: During a right partial nephrectomy, after the renal artery was clamped, a failure in the central CO(2) compressor compromised the pneumoperitoneum. Argon gas was delivered from an ABC at a flow rate of 4 L/min and a distance of 1 to 5 cm and directed toward the paranephric fat. RESULTS: Pneumoperitoneum was rapidly reestablished. Stable intra-abdominal pressure was maintained in the range of 14 to 20 mm Hg for 16 minutes until the original CO(2) supply was reestablished. The total warm ischemia time was 32 minutes. No hemodynamic changes were noted while using argon gas, and the procedure was completed successfully with an uneventful postoperative course. CONCLUSIONS: Argon gas delivery from an ABC can be used for emergency salvage of pneumoperitoneum in selected cases of acute CO(2) gas delivery failure and under strict intra-abdominal pressure monitoring.

Tratamento da ectasia vascular do antro gástrico por eletrocoagulação com argônio / Treatment of gastric antrum vascular ectasia with argon plasma coagulation

Introdução e objetivos: a ectasia vascular do antro gástrico (watermelon stomach) é uma causa rara de hemorragia digestiva aguda e crônica de difícil resposta a tratamento. a eletrocoagulação com argônio é um método de não contato que pode ser usado como alternativa ao laser em endoscopia. Neste estudo são apresentados resultados com o uso dessa técnica no tratamento da ectasia vascular do antro gástrico. Pacientes e métodos: foram analisados, retrospectivamente, seis pacientes (3M/3F; média de idade = 58,3 anos), com diagnóstico de ectasia vascular do antro gátrico tratados por eletrocoagulação com argônio em sessões mensais a uma potencia de 90w e fluxo de gás de 2l/min. Dois desses pacientes com ectasia vascular do antro gástrico não-cirrótico, houve resolução das lesões em dois casos e importante melhora endoscópica e sintomatica em outro dois. Nenhum desses pacientes, os quais se apresentavam clinicamente com hemorragia digestiva, necessitou de transfusões sanguineas após o termino da sessões com argônio, ou mesmo voltou a apresentar melena e /ou hematêmese. Conclusão: A eletrocoagulação com argônio é um tratamento seguro, efetivo e bem tolerado para a resolução do sangramento por ectasia vascular do antro gástrico. Essa técnica deve ser considerada terapêutica de primeira escolha no tratamento dessa afecção quando na ausênciade cirrose

Tratamento da retite actínica hemorrágica por eletrocoagulação com argônio / Treatment of radiation-induced rectitis by argoon plasma coagulation

Introdução e objetivos: A retite actínica hemorrágica é uma complicação de difícil manejo da radioterapia para cânceres da região pélvica. A eletrocoagulação com argônio é um metódo térmico de não contato que pose ser usado como alternativa ao laser em endoscopia. Este estudo apresenta os resultados com o uso desssa técnica no tratamento da retite actínica hemorrágica. Pacientes e métodos: Foram analisados retrospectivamente 12 pacientes (8M, 4F;média de idade = 74 anos) com retite actínica hemorrágica tratados por retossigmoidoscopia com eletrocoagulação com argônio em sessões mensais a potência de 50W e fluxo de gás de 2L/min. Resultados: Dez de 12 pacientes que completaram o tratamento apresentaram importante redução do sangramento retal ( sem a necessidade de novas transfusões de sangue) (n = 4) ou sua abolição total ( n = 6 ) por seguimento médiode 21 meses, após 2,4 sessões de eletrocoagulação com argônio, em média. Um paciente apresentou dor intensa após o procedimento e uma paciente desenvolveu uma estenose retal leve. Conclusões: A eletrocoagulação com argônio é um tratamento seguro, efetivo e bem tolerado para a resolução do sangramento por retite actínica. Esta técnica deve ser considerada a terapêutica de primeira escolha no tratamento da proctite hemorrágica por radioterapia

Resultados imediatos da eletrocoagulaçäo com argônio no tratamento do esôfago de Barrett em pacientes com e sem displasia / Endoscopic argon plasma coagulation (Beamer) of Barrett`s esophagus in patients with and without dysplasia

Intoduçäo e objetivo: O esôfago de Barrett (EB) é uma lesäo comprovadamente pré-maligna. As cirurgias anti-refluxo ou o tratamento farmacológico nem o revertem para epitélio escamoso, nem diminuem o risco de câncer associado a esta lesäo metaplásica. Recentemente, alguns estudos têm demonstrado reversäo do EB com diferentes técnicas endoscópicas associadas à inibiçäo ácida. Neste estudo os autores pretendem verificar se a reversäo completa do EB é possível através da APC. Métodos: foram tratados 32 pacientes -20M/12F, média etária =55,2 (21-84)- com EB demonstrado histologicamente com extensäo média de 3,9cm (0,5-6). Quatorze casos apresentavam displasia de baixo grau. Toda a extensäo do EB era cauterizada em cada sessäo usando o APC com uma potencia de 65-70W. Todos os pacientes recebiam 60mg de omeprazol durante o período de tratamento. Resultados: Reversäo completa do EB foi obtida em todos os pacientes após média de 1,9 sessäo (1-3). Esses resultados foram confirmados histologicamente por meio de múltiplas biópsias que evidenciaram epitélio escamoso. Dezessete (53por cento) pacientes sofreram dor retroesternal de forte a moderada intensidade com odinofagia por dois a dez dias após cada sessäo. Febre alta e derrame pleural ocorreram em cinco e estenose de esôfago em três desses 17 casos. Conclusäo: A eletrocoagulaçäo por argônio associada a supressäo ácida com omeprazol é um método efetivo em eliminar o EB, pelo menos, a curto prazo. Apenas estudos com seguimento a longo prazo desses pacientes, juntamente com alívio permanente do refluxo ( por cirurgia ou medicaçäo), poderäo determinar se essa técnica reduz ou elimina o risco de câncer associado ao EB

Welfare implications of gas stunning pigs: 3. The time to loss of somatosensory evoked potentials and spontaneous electrocorticogram of pigs during exposure to gases.

Changes in the spontaneous electrocorticogram (ECoG) and somatosensory evoked potentials (SEPs) were recorded in 12 pigs in each of three gas killing treatments. The treatments were 90% argon in air with 2% residual oxygen; a mixture of 30% carbon dioxide and 60% argon in air with 2% residual oxygen; or 80-90% carbon dioxide in air. The mean times to loss of SEPs were 15, 17 and 21 s, respectively. The mean time to loss of SEPs recorded during killing with a high concentration of carbon dioxide was significantly longer than those recorded for the other two gas killing treatments (P < 0.05). Slow waves (high amplitude and low frequency) appeared on average 15 s after exposure to argon. In some pigs killed with the carbon dioxide-argon mixture, a decrease in the frequency of electrical activity was apparent, although slow waves did not appear during killing with a higher concentration of carbon dioxide. A suppressed ECoG (reduction in amplitude of signals) was recorded at 22 and 20 s respectively, during exposure to the carbon dioxide-argon mixture and 80-90% carbon dioxide in air, but the onset of ECoG suppression could not be determined exactly during exposure to 90% argon in air. The time to onset of an isoelectric ECoG was 54, 39d and 32 s after exposure to argon, carbon dioxide-argon mixture and a high concentration of carbon dioxide, respectively. The mean time to the onset of an isoelectric ECoG during exposure to argon was significantly longer than that recorded for the other two gas killing treatments (P < 0.05). Based on the time to loss of SEPs, it is concluded that during killing with a high concentration of carbon dioxide, pigs would have to endure a moderate to severe respiratory distress induced with this gas for a considerable period of time prior to the loss of brain responsiveness. Argon-induced anoxia appears to be the first choice from a welfare point of view for killing pigs, based on its lack of aversive properties and its effectiveness in rapidly abolishing brain responsiveness. A mixture of 30% carbon dioxide and 60% argon in air is considered to be more humane than using a high concentration of carbon dioxide, as the time to loss of brain responsiveness is similar to that using 90% argon in air.

Carcase and meat quality in broilers either killed with a gas mixture or stunned with an electric current under commercial processing conditions.

1. Carcase and meat quality were evaluated under commercial conditions in 400 broilers either killed with a mixture of 30% carbon dioxide and 60% argon in air or stunned with a 50 Hz AC with clipped sine wave. 2. Compared with electrical stunning, killing broilers with the gas mixture eliminated or substantially reduced the prevalence of carcase and meat quality defects. 3. The results also showed that killing broilers with a mixture of 30% carbon dioxide and 60% argon would enable filleting (deboning) to be performed at 4 h post mortem without adversely affecting the cook loss or texture of breast meat.

Effects of breathing dense gas mixtures on cardiovascular function and EEG rhythms.

Gas mixtures containing oxygen and nitrogen or dense inert gases (sulfur hexafluoride, SF6, or argon, Ar) were inhaled by anaesthetized, artificially ventilated rabbits and cats. SF6 and Ar were compared to nitrous oxide (N2O), a dense inert gas well known for its anaesthetic properties. Concentrations in these gases were 50% (SF6) and 60% (Ar or N2O). In cats, there was a significant increase in total lung resistance with SF6 or Ar associated with a slight but significant drop in arterial blood pressure and heart rate (-5% and -10% with SF6 and Ar, respectively), with no change in electrocardiogram activity. N2O induced in some cats a slower electroencephalographic (EEG) pattern constituted by delta waves of higher amplitude, whereas neither SF6 nor Ar changed the EEG rhythms in this species. In the rabbits, the unsteadiness of the EEG rhythms did not make it possible to assess the cortical effects observed with SF6 or N2O.

Effect of inert gas switching at depth on decompression outcome in rats.

The present investigation was performed to determine whether inert gas sequencing at depth would affect decompression outcome in rats via the phenomenon of counterdiffusion. Unanesthetized rats (Rattus norvegicus) were subjected to simulated dives in either air, 79% He-21% O2, or 79% Ar-21% O2; depths ranged from 125 to 175 feet of seawater (4.8-6.3 atmospheres absolute). After 1 h at depth, the dive chamber was vented (with depth held constant) over a 5-min period with the same gas as in the chamber (controls) or one of the other two inert gas-O2 mixtures. After the gas switch, a 5- to 35-min period was allowed for gas exchange between the animals and chamber atmosphere before rapid decompression to the surface. Substantial changes in the risk of decompression sickness (DCS) were observed after the gas switch because of differences in potencies (He less than N2 less than Ar) for causing DCS and gas exchange rates (He greater than Ar greater than N2) among the three gases. Based on the predicted gas exchange rates, transient increases or decreases in total inert gas pressure would be expected to occur during these experimental conditions. Because of differences in gas potencies, DCS risk may not directly follow the changes in total inert gas pressure. In fact, a decline in predicted DCS risk may occur even as total inert gas pressure in increasing.

Low power argon laser trabeculoplasty.

Sixty-seven consecutive argon laser trabeculoplasties to as many patients were retrospectively followed-up for 3 to 12 (mean 7) months. The laser power used was substantially lower than originally proposed by Wise & Witter (1979) ranging from 100 mW to 500 mW. Factors influencing the outcome of low power trabebuloplasty were evaluated. The statistical analysis of the data was performed using multiple regression analysis, analysis of variance, t-test and chi 2-test. The mean success rate remained relatively low (33%). In the high power capsular glaucoma group it was 50%.