RESUMEN
Congenital tracheal stenosis in children is a rare, severe and life-threatening respiratory tract malformation characterized by respiratory failure. We have performed 74 surgical interventions in these patients under extracorporeal membrane oxygenation between 2013 and 2022. In this article, we present surgical treatment of a newborn with congenital tracheal stenosis. For the first time in the world, the patient underwent thoracoscopic resection and reconstruction of the trachea under extracorporeal membrane oxygenation.
Asunto(s)
Oxigenación por Membrana Extracorpórea , Estenosis Traqueal , Humanos , Recién Nacido , Estenosis Traqueal/congénito , Estenosis Traqueal/cirugíaRESUMEN
OBJECTIVE: To determine the optimal treatment of patients with complications of esophageal electrochemical burns by batteries. MATERIAL AND METHODS: There were 75 children with esophageal electrochemical burns by batteries between 2010 and 2019. All children underwent X-ray of the cervical spine, chest and abdomen, esophagoscopy with removal of the battery, tracheoscopy. Complications occurred in 39 children: TEF - 21, esophageal stenosis - 19, laryngeal paresis - 14, esophageal perforation - 3. Patients with TEF were divided into 2 groups: clinically stable children without respiratory failure and severe illness with respiratory failure including mechanical ventilation. Group I consisted of 6 children, four of them underwent laparoscopic Nissen fundoplication and gastrostomy. Group II consisted of 15 children. In acute period, 3 children underwent laparoscopic fundoplication and gastrostomy, 8 ones - TEF ligation, 4 patients - tracheal repair with esophageal flap and esophageal extirpation. Patients with esophageal stenosis underwent bougienage. Patients with esophageal perforation required therapy. Tracheostomy was necessary for respiratory failure and bilateral laryngeal paresis. Lateralization procedures were performed in patients with negative course of disease. RESULTS: In the 1st group, spontaneous closure of TEF was found in 3 children after fundoplication and gastrostomy. One child underwent thoracoscopic disconnection of TEF after reduction of fistula. In the 2nd group, fundoplication resulted spontaneous closure of fistula after 2-5 months. In 4 children, recanalization of the fistula or esophageal failure were observed in acute period after TEF ligation. CONCLUSION: Laparoscopic fundoplication and gastrostomy are optimal for TEF and can result complete or partial spontaneous closure of TEF. If radical procedure is necessary in acute period, tracheal repair with esophageal flap and extirpation of the esophagus with subsequent coloesophagoplasty should be considered.
Asunto(s)
Quemaduras , Atresia Esofágica , Perforación del Esófago , Estenosis Esofágica , Insuficiencia Respiratoria , Fístula Traqueoesofágica , Quemaduras/complicaciones , Niño , Atresia Esofágica/cirugía , Humanos , Paresia/complicaciones , Fístula Traqueoesofágica/diagnóstico , Fístula Traqueoesofágica/etiología , Fístula Traqueoesofágica/cirugíaRESUMEN
OBJECTIVE: To compare various methods of bile duct reconstruction in children with choledochal malformation (CM). MATERIAL AND METHODS: There were 99 children with CM over 10-year period. Mini-laparotomy (ML), laparoscopy (LS) and laparotomy (LT) were used. We performed radical CM resection and bile duct reconstruction using Roux-en-Y hepaticojejunostomy (RYHJ) and hepaticoduodenostomy (HD). Surgery time, short-term and long-term postoperative outcomes were evaluated. RESULTS: ML was performed in 39 patients, LS - 51 patients, LT - 9 patients. In case of LS, hospital-stay was significantly lower after intracorporeal RYHJ formation compared to extracorporeal technique (p=0.02, Mann-Whitney U-test). Intracorporeal RYHJ requires more time (p=0.0003). Intestinal passage recovered 3 times faster in the ML RYHJ group compared to the LS RYHJ group (p=0.016, Mann-Whitney U-test). ML RYHJ was followed by significantly less duration of postoperative narcotic anesthesia compared to LS HD (3 vs. 4 days, p=0.02, Mann-Whitney U-test). In our study, ML RYHJ has an advantage over LS RYHJ regarding long-term outcomes. HD resulted higher incidence of severe postoperative pancreatitis (p=0.033) that required surgical correction (LT, p=0.043). CONCLUSION: ML RYHJ has some advantages over other methods of bile duct reconstruction. Therefore, we can currently recommend this method as a preferable one.
Asunto(s)
Quiste del Colédoco , Laparoscopía , Anastomosis en-Y de Roux/efectos adversos , Niño , Quiste del Colédoco/diagnóstico , Quiste del Colédoco/cirugía , Conducto Colédoco , Humanos , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
OBJECTIVE: To evaluate an effectiveness of minilaparotomy in the treatment of choledochal malformation (CM) in children. MATERIAL AND METHODS: The study included children with CM who underwent surgery from January 2010 to May 2020. All patients were divided into 3 groups depending on surgical approach: minilaparotomy (ML), laparoscopy (LS) and laparotomy (LT). We analyzed surgery time, early postoperative outcomes and cosmetic results. RESULTS: There were 99 patients with CM for 10 years. ML was performed in 39 patients, LS - in 51 patients, and LT - in 9 patients. Significantly (p-value <0.001, Kruskal-Wallis test with Dunn paired comparison test, p<0.05) less surgery time was observed in ML group. According to Clavien-Dindo classification of surgical complications, we found a significant prevalence of complications in the LS group (p - 0.018, Kruskal-Wallis test). Moreover, LS was characterized by insignificant (p>0.05) predominance of the most severe complications requiring multiple redo surgeries. CONCLUSION: Currently, open surgery is a "gold standard" in the treatment of children with CM. LS is not preferred in children with CM. ML ensures favorable early outcomes in children with CM.
Asunto(s)
Quiste del Colédoco , Laparoscopía , Niño , Quiste del Colédoco/cirugía , Conducto Colédoco , Humanos , Laparoscopía/efectos adversos , Laparotomía/efectos adversos , Tempo Operativo , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/etiología , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
AIM: To compare early and long-term results of different surgical interventions in children with biliary atresia. MATERIAL AND METHODS: Retrospective analysis included medical records of children with biliary atresia who were treated at the Filatov Munitsipal Children's Hospital and National Medical Research Center for Obstetrics, Gynecology and Perinatology from 2000 to 2018. There were 91 patients. All patients were divided into three groups. Group 1 - conventional Kasai procedure (n=24), group 2 - laparoscopic Kasai surgery (n=45), group 3 - Kasai procedure through minimally invasive approach (n=22). Groups were comparable. RESULTS: Duration of Kasai procedure through minimally invasive approach was 69±12,97 min that was significantly less than in groups 1 and 2 (p1,3=0,006085; p2,3=0,000024). ICU-stay was minimal in group 3 (1.27±0.55 days, p1,3<0,05; p2,3<0,05). Abdominal drainage time was maximal in group 2 (11.28±6.37 days) and minimal in group 3 (5.86±2.39 days, p2,3=0.0002). Early and 2-year postoperative surgical efficiency was similar in all groups. There were no surgical complications in group 3. In group 2 one child had gastrointestinal bleeding followed by successful medication. There were 3 surgical complications in group 3: adhesive intestinal obstruction, small and large intestine perforation and 2 cases of gastrointestinal bleeding. There was one lethal outcome in the first group. Overall annual survival in children with native liver was 81.8%, 2-year - 51.7%. CONCLUSION: Kasai procedure through minimally invasive approach is justified and rational method with certain benefits of open and laparoscopic interventions and can be considered as a method of choice in treatment of children with biliary atresia.
Asunto(s)
Atresia Biliar/cirugía , Portoenterostomía Hepática/métodos , Niño , Humanos , Laparoscopía , Procedimientos Quirúrgicos Mínimamente Invasivos , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
AIM: To evaluate complications and long-term results of delayed esophagoesophagostomy in children with esophageal atresia (EA). MATERIAL AND METHODS: 165 EA children were operated at the Filatov Municipal Children's Hospital #13 for the period 2006-2016. Primary esophageal anastomosis was performed in 136 (82.4%) children with tracheoesophageal fistula. In 5 (3%) neonates with non-fistulous EA esophago- and gastrostomy were made for further coloesophagoplasty. Other 24 (14.5%) children underwent gastrostomy for delayed esophagoesophagostomy. 6 (25%) of them died within 12 days after admission. 18 survivors with gastrostomy subsequently underwent delayed esophagoesophagostomy. RESULTS: Postoperative complications occurred in 16 (88.9%) children. Esophageal anastomosis failure occurred in 4 (22.2%) patients, stenosis of anastomosis in 11 (61.1%) children, gastroesophageal reflux in 14 (77.8%) children. Early postoperative mortality was 16.7% (3 children). In remote period 92.3% of children were not adapted to normal diet and only in 7.7% of patients eating behavior corresponds to the age. 11 children underwent prolonged esophageal bougienage. 9 children underwent re-operation after delayed anastomosis. Esophageal extirpation was made in 4 children. CONCLUSION: Esophago- and gastrostomy provides 100% survival if primary esophageal anastomosis is impossible. Herewith, in children without esophagostomy mortality rate was 25%. We still can not confirm that delayed esophageal anastomosis is a good alternative for children with esophageal atresia. In view of our results the number of candidates for delayed esophageal anastomosis should be reduced.
Asunto(s)
Atresia Esofágica , Fístula Traqueoesofágica , Anastomosis Quirúrgica , Niño , Atresia Esofágica/cirugía , Gastrostomía , Humanos , Recién Nacido , Complicaciones Posoperatorias , Fístula Traqueoesofágica/cirugíaRESUMEN
The spectrum of pulmonary surgical pathology in newborns and infants is mainly presented by congenital diseases. Surgery is the main radical method of treatment of children with congenital lung diseases. By this time in the N.F.Filatov City Children's Hospital No13 it is performed more than 1000 endoscopic operations on the thoracic cavity including more than 300 lung resections. More than 190 cases were caused by congenital lung disease. The results of treatment of 194 infants with congenital lung disease for the period 2005-2014 are analyzed in this article. 14 (22%) patients were operated urgently. 8 patients (12%) with compensated respiratory failure underwent surgery at the age of 8 to 46 days. Children with absence of clinical manifestations underwent thoracoscopic lung resection at the age of 3 to 8 months. Thoracoscopic lobectomy was performed in the 40 cases (62%). There were no intraoperative complications. Thoracoscopic lung resection for malformations in newborns and infants is currently the method of choice. It allows to visualize pathological focus intraoperatively and to perform precise dissection of pulmonary root structures using modern equipment. Thus, it improves course of postoperative period and reduces duration of hospital-stay. Repeated lung resection in patients with recurrent tuberculosis of operated lung (literature review and own data).
Asunto(s)
Enfermedades Pulmonares/cirugía , Pulmón/anomalías , Neumonectomía/métodos , Toracoscopía/métodos , Adolescente , Niño , Preescolar , Femenino , Humanos , Imagenología Tridimensional , Lactante , Recién Nacido , Pulmón/cirugía , Enfermedades Pulmonares/congénito , Enfermedades Pulmonares/diagnóstico por imagen , Masculino , Estudios Retrospectivos , Tomografía Computarizada por Rayos XRESUMEN
AIM: To improve the results of surgical treatment of children with extended tracheal stenosis. MATERIAL AND METHODS: Since 2013 slidingtraÑheal plasty under extracorporeal membrane oxygenation was performed in 4 children aged 1 year 2 months - 4.5 years with extended tracheal stenosis in Children's City Clinical Hospital â13. Patients' weight was from 10,5 to 16 kg. Extended tracheal stenosis and complete cartilag inousrings were confirmed in all patients after peoperative survey. Indications for surgery were based on medical history data, the severity of respiratory failure and survey data. Sliding traÑheal plasty by different approach esunder extracorporeal membrane oxygenation was applied in all patients. RESULTS: There were no intraoperative complications. In the study group 1 patient died in remote postoperative period after discharge due to deterioration of his condition caused by upper respiratory tract infection and acute respiratory failure. In immediate postoperative period 1 patient had pronounced growth of granulation tissue in the area of anastomosis followed laser photocoagulation and prolonged intubation. The average ICU-stay was 24 days, the duration of mechanical ventilation - 11 days. Follow-up carefor patients was conducted on terms of 4-6 and 12 months after surgery. In 2 patients moderate complaints of recurrent bronchitis without signs of respiratory insufficiency during 6-8 months postoperatively were observed. In one child complaints were completely absent.
Asunto(s)
Oxigenación por Membrana Extracorpórea/métodos , Procedimientos de Cirugía Plástica/métodos , Insuficiencia Respiratoria/cirugía , Tráquea/cirugía , Estenosis Traqueal/cirugía , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino , Respiración Artificial , Insuficiencia Respiratoria/etiología , Estudios Retrospectivos , Federación de Rusia , Estenosis Traqueal/complicacionesRESUMEN
UNLABELLED: Question of feasibility of laparoscopic Kasai procedure and laparoscopic hepaticojejunostomy for biliary atresia (the BA) and choledochal cysts (the CC) in children has been a subject of discussion for a long time and still remains unsolved. AIM: To improve the results of surgery for biliary tract malformations (the BTM) in children using laparoscopic technique. MATERIALS AND METHODS: The are 55 patients with BA and CC, who were performed endosurgical operations, and 37 patients, who were performed traditional open surgical procedures. During this study we worked out and put into laparoscopic practice some new methods. We've made an analysis of technical features of liver transplantation after laparoscopic and traditional Kasai's operation in BA. RESULTS: The duration of laparoscopic Kasai procedure was significantly longer than open surgery (p < 0.05). In CC the duration was the similar (p > 0.05). There was no any urgent surgical complication after laparoscopic Kasai procedure in contrast to open surgery. We observed significantly fewer complications (40%) after laparoscopic hepaticojejunostomy than after traditional hepaticojejunoduodenostomy (84.6%, p < 0.05). The average length of stay in ICU and duration of analgesia after laparoscopy was significantly lower than after open surgery (p < 0.05). Comparing the efficiency of endosurgery and traditional operations using coloration of stool, decreasing of bilirubin level and the presence of indications to liver transplantation criteria we didn't find any significant difference (p > 0.05). CONCLUSION: At the same efficiency of laparoscopic and open reconstructive surgery for BA and CC the first has a number of incontrovertible advantages. Our experience allows us to recommend laparoscopic procedures to perform for the correction of BTM in children.
Asunto(s)
Atresia Biliar/cirugía , Quiste del Colédoco/cirugía , Laparoscopía/métodos , Adolescente , Atresia Biliar/diagnóstico , Niño , Preescolar , Quiste del Colédoco/diagnóstico , Humanos , Lactante , Recién Nacido , Trasplante de Hígado , Resultado del TratamientoRESUMEN
The problem of nutrition of schoolchildren as the main index of health status is considered. Recommendations for implementation of correction system of school feeding in conditions of Siberia will be presented. The purpose of work: on the basis of the results of monitoring living activity and assessment of the health of schoolchildren of different age groups in Siberia to develop guidelines on the rational balanced nutrition. Studies bear witness to inadequate diet and regimen of feeding of schoolchildren. In Siberia a progressive deterioration in the health of students during the years of learning is observed, part of diseases is associated with an unbalanced diet. We offer the project, in course of realization of which study in schools are carried out, scientifically grounded recommendations on appropriate diet and regimen of feeding for schoolchildren of different age groups in the Siberia in the cold and warm period of the year are developed. Implementation of recommendations will result in the general improvement of children health and reduction in medical aid appealability due to diseases of the gastrointestinal tract.
Asunto(s)
Servicios de Alimentación/normas , Estado de Salud , Necesidades Nutricionales , Estado Nutricional , Adolescente , Factores de Edad , Niño , Femenino , Guías como Asunto , Humanos , Masculino , Servicios de Salud Escolar , Instituciones Académicas , Siberia , Tiempo (Meteorología)RESUMEN
The article covers the 22-year experience of treatment of chemical burns of the esophagus in 4252 children. The cicatrical stricture (the III degree burn) of the esophagus had 5.9% of patients. 82% of all patients were aged 1-3 years. The endoscopic signs of esophageal burns, developed in clinic, allow the thorough differentiation of burn stages, which has certain influence on treatment strategy. Treatment strategies, depending on the stage of esophageal burn and chemical agent, were described. Methods and terms of gullet bougienage were analyzed.
Asunto(s)
Quemaduras Químicas/terapia , Esófago/lesiones , Preescolar , Femenino , Humanos , Lactante , MasculinoRESUMEN
Thoracoscopic and traditional methods of treatment of the inborn and acquired lung diseases in children were comparatively analyzed. The main group, operated on thoracoscopically, consisted of 30 patients. The control group, operated on thoracotomically, consisted of the same number of children. Both groups were comparable to the age, gender, diagnostic algorithm, risk and preoperative prepare. Traumaticity of the operation and postoperative period were assessed. Thoracoscopic method proved to have indisputable advantages.
Asunto(s)
Enfermedades Pulmonares , Pulmón , Dolor Postoperatorio , Neumonectomía , Toracoscopía , Analgésicos/uso terapéutico , Niño , Preescolar , Investigación sobre la Eficacia Comparativa , Técnicas de Diagnóstico del Sistema Respiratorio , Femenino , Humanos , Pulmón/anomalías , Pulmón/cirugía , Enfermedades Pulmonares/diagnóstico , Enfermedades Pulmonares/etiología , Enfermedades Pulmonares/cirugía , Masculino , Tempo Operativo , Dolor Postoperatorio/tratamiento farmacológico , Dolor Postoperatorio/prevención & control , Neumonectomía/efectos adversos , Neumonectomía/métodos , Periodo Posoperatorio , Proyectos de Investigación , Toracoscopía/efectos adversos , Toracoscopía/métodos , Resultado del TratamientoRESUMEN
The aortic arch and its branches anomalia compound 1-3.8% of all vessel inborn diseases. The treatment of such anomalia as tracheal vessel ring aims the liquidation of esophageal and tracheal compression. The authors introduce their experience of thoracoscopic tracheal vessel rings resection in 6 children. The time of the operation was 145±15min. There were no conversions to the traditional open surgery. The result was excellent in 4 of 6 children, who were completely releaed of tracheal obstruction symptoms. The rest 2 children demonstrated mild respiratory symptoms, cuased by the tracheomalation.
Asunto(s)
Aorta Torácica/anomalías , Aorta Torácica/cirugía , Toracoscopía/métodos , Tráquea/anomalías , Tráquea/cirugía , Obstrucción de las Vías Aéreas/etiología , Obstrucción de las Vías Aéreas/cirugía , Niño , Estenosis Esofágica/etiología , Estenosis Esofágica/cirugía , Humanos , LactanteRESUMEN
The thoracoscopic and traditional thoracotomic surgical access for bronchiectesis treatment in children were compared. The first (thoracoscopic) group included 18 children. The control (thoracotomic) group included 26 patients. The mean operative time in the 1st group was 78.3±31 min; pleural draining lasted for 1.3 days and postoperative hospital stay was 9.93±2.08 days. The mean operative time in the 2nd group was 81.7±35.1 min; pleural draining lasted for 3.3 days and postoperative hospital stay was 14.4±3.4 days. Conversion was needed in 4 cases. Therefor, the thoracoscopic surgery proved to be much more preferable in children because of its' minimal invasiveness.
Asunto(s)
Bronquiectasia/cirugía , Neumonectomía , Complicaciones Posoperatorias/prevención & control , Toracoscopía , Toracotomía , Adolescente , Bronquiectasia/diagnóstico , Bronquiectasia/etiología , Broncografía/métodos , Niño , Preescolar , Investigación sobre la Eficacia Comparativa , Femenino , Humanos , Pulmón/diagnóstico por imagen , Pulmón/cirugía , Masculino , Neumonectomía/efectos adversos , Neumonectomía/métodos , Cuidados Posoperatorios/métodos , Estudios Retrospectivos , Toracoscopía/efectos adversos , Toracoscopía/métodos , Toracotomía/efectos adversos , Toracotomía/métodos , Tomografía Computarizada Espiral/métodos , Resultado del TratamientoRESUMEN
Results of surgical treatment were comparatively analyzed in children with congenital lobar emphysema operated using traditional technique (1 group, 10 patients) and operated using thoracoscopic technique (2 group, 10 patients). In the first group average time of operation amounted 68 +/- 5,8 min., average time of plural drainage--3,3 days, average time of postoperative hospitalization--13,6 days and in the second group--62 +/- 15,6 min., 1,3 days and 7,4 days respectively. In the second group postoperative complications were not observed. In postoperative period one patient from the first group developed pneumothorax eliminated on the 5-th day after operation. Results of investigation indicate the advantages of thoracoscopic technique in treatment of children with lobar emphysema compared with traditional methods of treatment. Application of thoracoscopic technique in children with lobar emphysema is a serious alternative to traditional method due to slight postoperative period, lesser amount of complications and good cosmetic and functional results.
Asunto(s)
Enfisema Pulmonar/congénito , Adolescente , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Complicaciones Posoperatorias , Enfisema Pulmonar/cirugía , ToracoscopíaRESUMEN
Treatment results of 18 children operated on various biliary tract malformations were analyzed. Laparoscopic portoenteroanastomosis by Kasai was performed in 10 patients with biliary atresia aged from 10 days to 3,5 months. Average weight of the operated children was 3640 +/- 124 g. 8 patients aged from 2 to 15 years operated on cystic common bile duct malformation. Laparoscopic dissection of cystic deformated biliary ducts with Roux-en-Y hepaticoenterostomy was performed in these cases. 5 troacars were used for both operations. First stage of portoenteroanastomosis formation represented of laparoscopic portal fibrous plate separation. By cystic common bile duct malformations, altered bile ducts were dissected. The second stage--Roux-en-Y enteroenteroanastomosis--was performed through a paraumbilical microincision. Portal anastomosis or common bile duct anastomosis was performed also laparoscopically. Recovery of patients was observed in all cases. Early postoperative course demonstrated a low invasiveness of the method. Thus, laparoscopic access can become a method of choice in treatment of biliary tract malformations in children.
Asunto(s)
Enfermedades de las Vías Biliares/cirugía , Sistema Biliar/anomalías , Laparoscopía/métodos , Procedimientos de Cirugía Plástica/métodos , Adolescente , Anastomosis Quirúrgica , Enfermedades de las Vías Biliares/congénito , Enfermedades de las Vías Biliares/diagnóstico , Niño , Preescolar , Estudios de Seguimiento , Humanos , Lactante , Recién Nacido , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
Information on atmospheric parameters, properties and processes above 70 km are mainly based upon meteor data. An important problem of such data systematization is to single out the meteor streams associated with a series of extreme phenomena. The forecasting of these phenomena requires a physical model of meteor streams at the early stage of their occurrence. A direct coupling with comets is assumed for most of the streams. This paper analyses the structure simulation of cometary nucleus desintegration. The D-criterion is used as the orbital community criterion. Giacobini-Zinner comet in its ten appearances (1900-1979) is considered. Determination of stream location and its detailed structural characteristics is essential for long space missions.
Asunto(s)
Medio Ambiente Extraterrestre , Meteoroides , Modelos Teóricos , Fenómenos Astronómicos , AstronomíaRESUMEN
Complex numerical model of young meteor stream formation taking into account reactive deceleration of cometary nucleus and its form change in the process of stream formation is discussed. The model made it possible to predict the existence of fine and superfine structures for young meteor streams, the characteristics of which agree with the observational data on the Draconid and Leonid meteor showers.
Asunto(s)
Medio Ambiente Extraterrestre , Meteoroides , Modelos Teóricos , Fenómenos Astronómicos , Astronomía , Hielo , MatemáticaRESUMEN
A method is described for reconstruction of certain sarcolemma characteristics of smooth muscle cells in the small intestine of a rabbit on the planar lipid membranes (PLM). The method is based on the use of fusogenic properties of certain lipid preparations. The ultrasound dispergates of azolectin and egg lecithin in combined incubation with sarcolemma vesicles of smooth-muscle cells promote a 1.4-1.8-fold increase of the total ATPase activity of the sarcolemma. Cholesterol, dipalmithoil lecithin, total brain phospholipids, inhibit the ATPase activity. Sarcolemma vesicles preincubated with azolectin lyposomes in the ratio which induces maximum ATPase activation (sarcolemma protein: azolectin-1:6) interact intensively with PLM from azolectin. PLM modified in such a way is channel-conductive, sensitive to tetraethylammonium and sign of the applied voltage.