RESUMO
PURPOSE: To examine updated evidence on the efficacy and safety of mesh non-fixation in patients undergoing laparo-endoscopic repair of groin hernias. METHODS: We searched MEDLINE, Cochrane Central Library, Embase, ClinicalTrials. gov, and ICTRP databases to identify randomized controlled trials. The primary outcomes were recurrence, chronic pain, and return to daily life. The certainty of evidence (CoE) was assessed by grading recommendations, assessments, developments, and evaluations. We performed a subgroup analysis based on the surgical type. This study was registered with PROSPERO (CRD 42022368929). RESULTS: We included 25 trials with 3,668 patients (4,038 hernias) were included. Mesh non-fixation resulted in little to no difference in hernia recurrence (relative risk [RR]:1.40, 95% confidence interval [CI]:0.59-3.31; I2 = 0%; moderate CoE) and chronic pain (RR:0.48, 95% CI:0.13-1.78; I2 = 77%; moderate CoE), but reduced return to daily life (mean difference [MD]: - 1.79 days, 95% CI: - 2.79 to -0.80; I2 = 96%; low CoE). In subgroup analyses, the transabdominal preperitoneal approach (TAPP) (MD: - 2.97 days, 95% CI: - 4.87 to - 1.08; I2 = 97%) reduced return to daily life than total extraperitoneal inguinal approach (MD: - 0.24 days, 95% CI - 0.71 to 0.24; I2 = 61%) (p = 0.006). CONCLUSIONS: Mesh nonfixation improves the return to daily life without increasing the risk of hernia recurrence or chronic pain. Surgeons and patients may discuss mesh nonfixation options to accommodate a patient's desired return to daily life. Further trials focusing on TAPP are required to confirm these findings.
Assuntos
Dor Crônica , Hérnia Inguinal , Laparoscopia , Humanos , Laparoscopia/métodos , Telas Cirúrgicas/efeitos adversos , Dor Crônica/etiologia , Dor Crônica/cirurgia , Virilha/cirurgia , Herniorrafia/efeitos adversos , Herniorrafia/métodos , Hérnia Inguinal/cirurgia , Recidiva , Resultado do Tratamento , Dor Pós-Operatória/cirurgiaRESUMO
BACKGROUND: In small infants, left lateral segment grafts are sometimes too large to overcome the problems of large-for-size grafts in the abdominal compartment. To address this problem, we have developed a safe living donor graftectomy for neonates, a so-called "S2 monosegment graft" to minimize graft thickness. We reviewed our single-center experience to evaluate the feasibility of this technique for reducing graft size. METHODS: Eleven living-donor liver transplants using S2 monosegment grafts were performed between October 2008 and September 2014 at our institution. Medical records of both donors and recipients were reviewed and data collected retrospectively. RESULTS: The mean age of recipients at the time of transplantation was 125.3 days, including 3 neonates. The average S2 monosegment graft weight was 127.4 g, and the graft-to-recipient body weight ratio was successfully reduced to 3.5%. The graft livers were reduced to 4.1 cm in thickness. Two recipients with grafts larger than 5 cm could not undergo primary abdominal closure. Portal vein stenosis and biliary stenosis was observed in 1 recipient, and hepatic artery complications were seen in 2 recipients; the clinical course for all donors were uneventful. Liver regeneration was seen in every patient. The graft and patient 1-year survival rate was 100%. CONCLUSIONS: Living-donor liver transplantation using S2 monosegment grafts offers a safe and useful option for treating smaller infants. Here, we introduce our method of S2 monosegment graft emphasizing the donor harvest and graft thickness.
Assuntos
Falência Hepática/cirurgia , Transplante de Fígado/métodos , Doadores Vivos , Adulto , Seleção do Doador , Estudos de Viabilidade , Feminino , Humanos , Lactente , Recém-Nascido , Falência Hepática/diagnóstico por imagem , Falência Hepática/mortalidade , Masculino , Duração da Cirurgia , Estudos Retrospectivos , Taxa de Sobrevida , Resultado do TratamentoRESUMO
PURPOSE: This retrospective study evaluates the clinical course and outcomes of patients who underwent surgery for strangulated hernias. METHODS: Among 520 groin hernias from 2001 to 2012, 51 inguinal and 42 femoral hernias were strangulated and operated emergently at a tertiary referral center. Perioperative factors, patient profiles, and time interval to surgery (T total = time from onset to surgery, T 1 = time from onset to initial evaluation, T 2 = time from the first hospital to the tertiary center, T 3 = time from admission at the tertiary center to surgery, T total = T 1 + T 2 + T 3) were analyzed in patients with strangulation, then compared between two groups, the bowel resection (BR) group and the non-bowel resection (NBR) group. RESULTS: T 1, T 2 and T total in the bowel resection group were significantly longer than those in the non-bowel resection group (P < 0.05). Patients who presented initially to the tertiary center (T 2 = 0) had a significantly lower resection rate than patients transported from other hospitals (24 vs. 44 %, P = 0.048). There was no significant difference in morbidity between the BR and NBR groups (35 vs. 24 %, P = 0.231). CONCLUSIONS: The elapsed time from onset to surgery, especially T 1 and T 2, is the most important prognostic factor in patients with strangulated groin hernias. Early diagnosis and transportation are essential for good outcomes.
Assuntos
Hérnia Femoral/cirurgia , Hérnia Inguinal/cirurgia , Idoso , Idoso de 80 Anos ou mais , Emergências , Feminino , Hérnia Femoral/complicações , Hérnia Inguinal/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de TempoRESUMO
BACKGROUND AND STUDY AIMS: Only a few large cohort studies have evaluated the efficacy and safety of endoscopic necrosectomy for infected walled-off pancreatic necrosis (WOPN). Therefore, a multicenter, large cohort study was conducted to evaluate the efficacy and safety of endoscopic necrosectomy and to examine the procedural details and follow-up after successful endoscopic necrosectomy. PATIENTS AND METHODS: A retrospective review was conducted in 16 leading Japanese institutions for patients who underwent endoscopic necrosectomy for infected WOPN between August 2005 and July 2011. The follow-up data were also reviewed to determine the long-term outcomes of the procedures. RESULTS: Of 57 patients, 43 (75 %) experienced successful resolution after a median of 5 sessions of endoscopic necrosectomy and 21 days of treatment. Complications occurred in 19 patients (33 %) during the treatment period. Six patients died (11 %): two due to multiple organ failure and one patient each from air embolism, splenic aneurysm, hemorrhage from a Mallory - Weiss tear, and an unknown cause. Of 43 patients with successful endoscopic necrosectomy, recurrent cavity formation was observed in three patients during a median follow-up period of 27 months. CONCLUSIONS: Endoscopic necrosectomy can be an effective technique for infected WOPN and requires a relatively short treatment period. However, serious complications can arise, including death. Therefore, patients should be carefully selected, and knowledgeable, skilled, and experienced operators should perform the procedure. Further research into safer technologies is required in order to reduce the associated morbidity and mortality.
Assuntos
Endoscopia do Sistema Digestório , Pâncreas/patologia , Pâncreas/cirurgia , Pancreatopatias/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Drenagem , Endoscopia do Sistema Digestório/efeitos adversos , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Necrose/microbiologia , Necrose/cirurgia , Recidiva , Estudos Retrospectivos , Stents , Irrigação Terapêutica , Adulto JovemRESUMO
INTRODUCTION: Laparoscopic splenectomy using pneumoperitoneum has been performed since 1992. The gasless abdominal wall-lifting method for laparoscopic splenectomy was introduced as an alternative. This retrospective study was undertaken to compare results using the two techniques. METHODS: Between 1995 and 2010, 54 patients underwent laparoscopic splenectomy at a single institution; 30 underwent the procedure using the gasless technique and 24 using pneumoperitoneum. There were no significant differences between the two groups regarding age, sex or BMI, but more patients underwent concurrent operations in the pneumoperitoneum group. The abdominal wall-lift system with subcutaneous K-wires was used for the gasless method. RESULTS: Intraoperative blood loss was similar in the two groups (193.0 ± 196.7 mL gasless, 217.3 ± 296.6 mL pneumoperitoneum; P > 0.05), but operative time (182.1 ± 92.1 min, 135.1 ± 46.1 min; P < 0.05), and resected spleen weight (306.1 ± 297.7 g, 138 ± 81.0 g; P < 0.05) were significantly different. In the gasless group, additional procedures included conversion (n = 1), mini-laparotomy (n = 2), and CO(2) insufflation (n = 2). Excluding the concurrent living-related kidney donor patients, hospital stay was similar (6.9 ± 2.5 days, 6.3 ± 2.0 days, P > 0.05). CONCLUSION: Although gasless laparoscopic splenectomy is feasible, there are disadvantages, particularly the restricted operative working space in some patients. These results suggest that either technique may be used on an individual basis in patients undergoing laparoscopic splenectomy.
Assuntos
Parede Abdominal/cirurgia , Laparoscopia/métodos , Pneumoperitônio Artificial , Esplenectomia/métodos , Adolescente , Adulto , Idoso , Anemia Hemolítica/cirurgia , Criança , Cistos/cirurgia , Feminino , Humanos , Laparoscopia/instrumentação , Linfoma/cirurgia , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Esplenectomia/instrumentação , Esplenopatias/cirurgia , Trombocitopenia/cirurgia , Resultado do Tratamento , Adulto JovemRESUMO
Recent advances in multidetector row computed tomography (MD-CT) technology provide new opportunities for clinical diagnoses of various diseases. Here we assessed CT virtual duodenoscopy, duodenography, and three-dimensional (3D) multicholangiography created by MD-CT for clinical diagnosis of duodenal malignant lesions. The study involved seven cases of periduodenal carcinoma (four ampullary carcinomas, two duodenal carcinomas, one pancreatic carcinoma). Biliary contrast medium was administered intravenously, followed by intravenous administration of an anticholinergic agent and oral administration of effervescent granules for expanding the upper gastrointestinal tract. Following intravenous administration of a nonionic contrast medium, an upper abdominal MD-CT scan was performed in the left lateral position. Scan data were processed on a workstation to create CT virtual duodenoscopy, duodenography, 3D multicholangiography, and various postprocessing images, which were then evaluated for their effectiveness as preoperative diagnostic tools. Carcinoma location and extent were clearly demonstrated as defects or colored low-density areas in 3-D multicholangiography images and as protruding lesions in virtual duodenography and duodenoscopy images. These findings were confirmed using multiplanar or curved planar reformation images. In conclusion, CT virtual duodenoscopy, doudenography, 3-D multicholangiography, and various images created by MD-CT alone provided necessary and adequate preoperative diagnostic information.
Assuntos
Colangiografia/métodos , Neoplasias Duodenais/diagnóstico por imagem , Duodeno/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Tomografia Computadorizada por Raios X/métodos , Idoso , Idoso de 80 Anos ou mais , Ampola Hepatopancreática/diagnóstico por imagem , Carcinoma/diagnóstico por imagem , Neoplasias do Ducto Colédoco/diagnóstico por imagem , Meios de Contraste , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Invasividade Neoplásica , Neoplasias Pancreáticas/diagnóstico por imagem , Interpretação de Imagem Radiográfica Assistida por Computador/métodos , Interface Usuário-ComputadorRESUMO
Although hand-assisted laparoscopic surgery (HALS) is very common in various laparoscopic procedures, it is rarely used for retroperitoneal endoscopic adrenalectomy because of the small working area. The authors evaluate HALS in endoscopic adrenalectomy with respect to its use as a rescue procedure in complicated cases. In their department, 47 patients underwent endoscopic adrenalectomies between 1998 and 2004. Mainly because of complicated anatomy, three primary aldosteronism cases were converted to retroperitoneal HALS. This involved making an additional 6 cm skin incision, into which the surgeon's left hand was inserted, with the palm used to create a sufficient visual field and working area. The fingers were used for tactile sensation and blunt resection. For these three cases, successful retroperitoneal HALS in endoscopic adrenalectomy resulted in no mortality or morbidity. These findings indicate that this procedure is a feasible technique for complicated benign adrenal tumor cases.
Assuntos
Adrenalectomia/métodos , Endoscopia/métodos , Hiperaldosteronismo/cirurgia , Laparoscopia/métodos , Espaço Retroperitoneal , Terapia de Salvação/métodos , Estudos de Viabilidade , Feminino , Mãos , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do TratamentoRESUMO
BACKGROUND: We sought to validate computed tomographic virtual pancreatoscopy (CT-VP) created by multidetector row CT (MD-CT) in the clinical diagnosis of intraductal papillary mucinous neoplasm (IPMN) of the pancreas. METHODS: Five cases of pancreatic IPMNs were included in this study. A nasopancreatic drainage tube was inserted and the pancreatic duct was filled with contrast medium, after which an upper abdominal scan was performed by MD-CT. CT-VP and three-dimensional (3D) CT pancreatographic images were created using a workstation and compared with images by conventional diagnostic techniques. All cases were evaluated by endoscopic retrograde pancreatography (ERP) and three cases of main duct type were assessed by intraoperative real pancreatoscopy (RP). RESULTS: In the main duct cases, papillary projections in the main pancreatic duct and branch orifices were clearly detected by CT-VP. These lesions and structures were confirmed by intraoperative RP, and the CT-VP images were clearer than RP images. In branch cases, a surface-rendering method allowed protruding lesions to be clearly detected in the dilated branches. CONCLUSION: Compared with conventional ERP or RP, CT-VP and 3D-CT pancreatographic images were finer in quality, and the procedures were less invasive, faster, and less expensive. The potential shown by CT-VP with 3D-CT pancreatography in the clinical diagnosis of pancreatic IPMNs suggests that this approach may replace ERP in the near future.
Assuntos
Adenocarcinoma Mucinoso/diagnóstico por imagem , Adenocarcinoma Papilar/diagnóstico por imagem , Carcinoma Ductal Pancreático/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Idoso , Meios de Contraste , Diagnóstico Diferencial , Feminino , Humanos , Imageamento Tridimensional , Masculino , Pessoa de Meia-Idade , Interpretação de Imagem Radiográfica Assistida por ComputadorRESUMO
Recently, artificial ion conductors have been prepared by growing epitaxial heterolayers consisting of BaF2-CaF2 using molecular beam epitaxy. The ionic conductivity of these heterolayers shows a strong dependence on the layer thickness [N. Sata, S. Eberman, K. Eberl, and J. Maier, Nature 408, 996 (2000)]. In this paper three such heterolayers with different spacings (sample A: 80 nm, sample B: 10 nm, sample C: 1 nm) are investigated by conventional transmission electron microscopy and high-resolution transmission electron microscopy. The spacings are chosen such that they fall into the three conductivity regimes observed in N. Sata et al. (l > 50 nm; 8 < l < 50 nm; l < 8 nm). In accordance with conductivity studies, the samples with spacings of 10 nm or greater (A,B) are epitaxial and continuous, whereas in the case of extremely small spacing (C) the continuity of the layers is destroyed by formation of a column-like structure. Analytical electron microscopy reveals that, instead of forming multilayers, Ca and Ba separate in different columns in sample C. The structure properties of sample A (large l) are quite ideal: Planar interfaces with regular arrays of misfit dislocations with their Burgers vectors on the interface are observed. In the case of sample B (medium l) the lattice misfit is accommodated, in addition, by wavy interfaces associated with dislocations characterized by a Burgers vector that makes a large angle to the interfaces. The (111) lattice spacing very close to the interfaces is markedly changed due to this novel relaxation mechanism in the multilayer. The influences of the crystallographic defects on the ionic conductivity are also discussed.
RESUMO
The antimicrobial properties of the hexane extract from the leaves and twigs of the Eupatorium glutinosum was tested against two Gram-negative and two Gram-positive bacteria. Bioassay guided fractionation leads characteristically to isolation and structure elucidation of two active compounds: 15-hydroxy-7-labden-17-oic acid and its acetate. These results validate the vernacular medicinal uses of the plant in folkloric medicine. Dammara-20, 24-dien-3-acetate, stigmasterol and epi-friedelanone have been also isolated in addition to the palmitate of nepehinol for the first time as naturally occurring.
Assuntos
Antibacterianos/farmacologia , Diterpenos/farmacologia , Eupatorium , Antibacterianos/química , Antibacterianos/isolamento & purificação , Diterpenos/química , Diterpenos/isolamento & purificação , Testes de Sensibilidade Microbiana/métodos , Casca de Planta , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de PlantaRESUMO
BACKGROUND/AIMS: Pancreatic cancer remains one of the most formidable tumors defying early detection and effective treatment. Long-term survivors, however, do exist after resection. We investigated the clinicopathologic features of patients with pancreatic cancer who survived more than 5 years to draw out some suggestions concerning the indication of surgical treatment. METHODOLOGY: We studied the clinicopathologic features of 13 patients with pancreatic cancer who survived more than 5 years after resection. We reviewed their clinical records to investigate preoperative symptoms, serum tumor markers, operative findings, postoperative adjuvant therapy, and modes of recurrence and survival periods. Information on the location, size, histology and spread of the primary tumors were mainly obtained from pathology reports. RESULTS: Histologic types of the long survivors included ductal adenocarcinoma of common type in 4 patients, mucinous noncystic adenocarcinoma in 2, intraductal papillary-mucinous carcinoma (invasive) in 4, undifferentiated carcinoma in 1, endocrine tumor (islet cell carcinoma) in 1 and acinar cell carcinoma in 1. All 4 cases of ductal adenocarcinoma of the common type showed a moderate invasion either to the retroperitoneum, the portal vein or the duodenum. Two patients with mucinous noncystic carcinoma attained a long survival despite extensive invasion of the pancreatic stroma, although one died of peritoneal carcinomatosis. Two of 4 patients with intraductal papillary-mucinous cancer (invasive) died of peritoneal dissemination 6 and 11 years after resection, respectively. Three patients with cancer of other special histologic types, i.e., undifferentiated, well-differentiated endocrine carcinoma and acinar cell carcinoma, showed invasion of the portal vein and splenic artery, involvement of the retroperitoneum and a metastatic tumor in the liver, respectively. CONCLUSIONS: Whereas special histologic types including ductal variants tended to predispose to long-term survival, ductal adenocarcinoma of the common type had some chance of long survival even with invasion of the surrounding tissues.
Assuntos
Adenocarcinoma Mucinoso/mortalidade , Adenocarcinoma Mucinoso/cirurgia , Carcinoma Ductal Pancreático/mortalidade , Carcinoma Ductal Pancreático/cirurgia , Neoplasias Pancreáticas/mortalidade , Neoplasias Pancreáticas/cirurgia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Nonylphenol (NP) is an important intermediate in the production of various commercial and industrial materials, but is also known as a ubiquitous pollutant in urban aquatic environments. We recently studied the NP-degrading activities of microflora in several aquatic environments, and found a notable degrading activity for wastewater from a sewage treatment plant in Tokyo. This result led us to isolate NP-degrading microbes and identify biodegradation products. Using conventional plate culture techniques and molecular biological methods, Pseudomonas and Sphingomonas species, which are known for their degradation activities of many aromatic compounds, have been isolated. But it has also been found that Sphingomonas sp. (S-strain) is necessary and sufficient for the degradation of NP. Although the role of Pseudomonas sp. (P-strain) remains unclear, P-strain seems to provide some co-nutrients for the growth of S-strain. The degradation products were analyzed by GC/MS and NMR. More than 95% of NP was degraded within 10 days and aromatic compounds other than NP were not found, suggesting that the phenolic part of NP was completely degraded. We also examined the potential of S-strain for bioremedial applications. S-strain cells immobilized on chitosan or alginate beads retain their NP-degrading activity in flask-scale experiments. Furthermore, the chitosan-bound cells in a lab-scale bioreactor have been found to be persistent for repeated use, suggesting that S-strain is applicable to the treatment of NP-contaminated wastewater.
Assuntos
Fenóis/metabolismo , Pseudomonas/metabolismo , Sphingomonas/metabolismo , Poluentes Químicos da Água/metabolismo , Sequência de Bases , Biodegradação Ambiental , Reatores Biológicos , Primers do DNA , Cromatografia Gasosa-Espectrometria de Massas , Espectroscopia de Ressonância Magnética , FilogeniaRESUMO
A novel sulfur-containing amino acid, pulcherrimine, has been isolated as a bitter principle from ovaries of the sea urchin Hemicentrotus pulcherrimus. The structure was elucidated as 4-(2'-carboxy-2'-hydroxy-ethylthio)-2-piperidinecarboxylic acid by spectroscopic and chemical methods. Absolute stereochemistry was determined by NOE experiments and chiral HPLC analysis. Pulcherrimine exhibited bitterness with a threshold value of 0.306 mM.
Assuntos
Aminoácidos Sulfúricos/química , Piperidinas/química , Ouriços-do-Mar , Paladar , Aminoácidos Sulfúricos/isolamento & purificação , Animais , Feminino , Estrutura Molecular , Ovário/química , Piperidinas/isolamento & purificação , Alimentos MarinhosRESUMO
The early diagnosis of pancreatic carcinoma is essential for increasing patient survival rates. In this study, 52 patients with suspected pancreatic diseases were examined to investigate the value of K-ras codon 12 point mutation, levels of carcinoembryonic antigen (CEA) and carbohydrate antigen (CA19-9), and cytology of pancreatic juice in the diagnosis of pancreatic carcinoma. Pancreatic juice was taken without secretin stimulation. K-ras mutation was detected by enriched polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP). K-ras mutation in pancreatic juice was more frequent in carcinoma than in benign diseases (P = 0.0448). The positive predictive value of K-ras mutation for the diagnosis of neoplastic disease was 83%. The CEA level in pancreatic juice in carcinoma was significantly greater than that in benign disease (P< 0.0001). When the cutoff level of CEA was set at 50 ng/ml, its accuracy for the diagnosis of carcinoma was 85%. A multivariate analysis showed that K-ras mutation and CEA level in pancreatic juice, as well as serum CA19-9 level and age of the patient were independent variables for the diagnosis of carcinoma, and the accuracy of diagnosis by this analysis was increased to 90%. In conclusion, both K-ras mutation and CEA level in pancreatic juice may be valuable for the diagnosis of carcinoma. Better discrimination was possible with a multivariate analysis.
Assuntos
Biomarcadores Tumorais/análise , Antígeno Carcinoembrionário/análise , Carcinoma/diagnóstico , Genes ras , Neoplasias Pancreáticas/diagnóstico , Mutação Puntual , Adulto , Idoso , Sequência de Bases , Carcinoma/genética , Carcinoma/patologia , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Suco Pancreático/química , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Valor Preditivo dos Testes , Probabilidade , Prognóstico , Sensibilidade e Especificidade , Estatísticas não ParamétricasRESUMO
Leaf-movement in nyctinastic plants has long been believed to be controlled by plant hormones that are common among all nyctinastic plants. We have identified several bioactive substances for nyctinasty, whose bioactivities were highly specific to the original plant, based on the bioassay using the original plant leaf, and have shown that nyctinastic leaf-movement is not regulated by plant hormones. Our present results are in accordance with Umrath et al. physiologically significant opinion.
Assuntos
Fabaceae/fisiologia , Folhas de Planta/fisiologia , Plantas Medicinais , Bioensaio/métodos , Fabaceae/química , Folhas de Planta/químicaRESUMO
Ion conduction is of prime importance for solid-state reactions in ionic systems, and for devices such as high-temperature batteries and fuel cells, chemical filters and sensors. Ionic conductivity in solid electrolytes can be improved by dissolving appropriate impurities into the structure or by introducing interfaces that cause the redistribution of ions in the space-charge regions. Heterojunctions in two-phase systems should be particularly efficient at improving ionic conduction, and a qualitatively different conductivity behaviour is expected when interface spacing is comparable to or smaller than the width of the space-charge regions in comparatively large crystals. Here we report the preparation, by molecular-beam epitaxy, of defined heterolayered films composed of CaF2 and BaF2 that exhibit ionic conductivity (parallel to the interfaces) increasing proportionally with interface density--for interfacial spacing greater than 50 nanometres. The results are in excellent agreement with semi-infinite space-charge calculations, assuming a redistribution of fluoride ions at the interfaces. If the spacing is reduced further, the boundary zones overlap and the predicted mesoscopic size effect is observed. At this point, the single layers lose their individuality and an artificial ionically conducting material with anomalous transport properties is generated. Our results should lead to fundamental insight into ionic contact processes and to tailored ionic conductors of potential relevance for medium-temperature applications.
RESUMO
BACKGROUND/AIMS: A large, sustained increase in acinar [Ca2+]i may play a key role in the pathogenesis of acute pancreatitis. Many mechanisms which lead to cell damage in vitro and pancreatitis in vivo, such as free radicals or supraphysiological cerulein concentrations, cause a rapid increase in [Ca2+]i in pancreatic acinar cells. Little is known about why [Ca2+]i increases in some instances stimulate secretion and in other instances initiate cell death. So far, [Ca2+]i increases were thought to represent physiological signals when they occurred as oscillations at the single cell level. METHODOLOGY: This paper reviews recent literature and our own original research about the role of calcium in the function of pancreatic acinar cells and the development of pancreatitis. RESULTS: Recent studies showed that exposure of acinar cells to free radicals not only caused a bulk increase in [Ca2+]i but also resulted in calcium oscillations which had a lower frequency than, but similar amplitude to oscillations occurring after physiological stimuli. The absolute increase in [Ca2+]i did not definitely determine the cellular response. Instead, the duration of [Ca2+]i increase may have been more important. In contrast to previous belief of a direct relationship between [Ca2+]i oscillations and exocytosis, recent results show that radicals can induce [Ca2+]i oscillations which do not exert exocytosis but inhibit the secretory response to physiological stimuli. Further experiments showed that the [Ca2+]i release caused by radicals originates from thapsigargin-insensitive, ryanodine-sensitive stores. CONCLUSIONS: The origin and duration of [Ca2+]i increases rather than their extent or oscillatory nature, determine whether the cell will secrete or die. An abnormal [Ca2+]i increase can trigger trypsin activation, acinar cell damage and acute pancreatitis. This hypothesis is supported by studies which show that calcium chelators inhibit radical-induced trypsin activation as well as cell necrosis and apoptosis. Thus, an inhibition of pathological [Ca2+]i release may have a therapeutic potential.
Assuntos
Cálcio/fisiologia , Pancreatite/fisiopatologia , Doença Aguda , Animais , Apoptose/fisiologia , Autólise/fisiopatologia , Ceruletídeo/fisiologia , Colecistocinina/fisiologia , Endopeptidases/fisiologia , Exocitose/fisiologia , HumanosRESUMO
Aurantosides D-F (4-6), new polyene tetramic acids comprising an N-trisaccharide unit, have been isolated from the marine sponge Siliquariaspongia japonica. Their structures were determined by spectral and chemical methods. A reinvestigation of NMR data of the previously isolated aurantosides A and B led to revision of the geometry of the terminal double bond. Aurantosides exhibit potent antifungal activity against Aspergillus fumigatus and Candida albicans.
Assuntos
Antifúngicos/isolamento & purificação , Glicosídeos/isolamento & purificação , Poríferos/química , Pirrolidinonas/isolamento & purificação , Animais , Antifúngicos/farmacologia , Aspergillus fumigatus/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Glicosídeos/farmacologia , Leucemia P388/tratamento farmacológico , Espectroscopia de Ressonância Magnética , Camundongos , Testes de Sensibilidade Microbiana , Pirrolidinonas/farmacologia , Espectrometria de Massas de Bombardeamento Rápido de ÁtomosRESUMO
Little is known as yet about the role of apoptosis in pancreatic damage. This study evaluated the effects of supraphysiologic concentrations of the cholecystokinin (CCK) analog, cerulein, which causes cell damage in vitro and acute pancreatitis in vivo, on cell proliferation and DNA fragmentation in the rat pancreatic acinar cell line AR4-2J. Cerulein inhibited the cell proliferation of AR4-2J time- and dose-dependently to approximately 60% of the control level at 10(-6) M after 72 h. DNA fragmentation, as assessed by both electrophoresis and enzyme-linked immunosorbent assay (ELISA), occurred at cerulein concentrations > or = 10(-8) M. The maximal DNA fragmentation as measured by ELISA was reached after 24 h. Cerulein at concentrations > or = 10(-9) M induced wild-type p53. Glutathione (1 mM) diminished the effects of cerulein on both cell proliferation and DNA fragmentation, whereas spermine (100 microM), which partially attenuated DNA fragmentation, did not have an effect on cell proliferation. The CCK-A-receptor antagonist loxiglumide completely abolished the effect of cerulein on DNA fragmentation. The serine-protease inhibitor FUT-175 (10 microM), the cysteine-protease inhibitor NCO-700 (5 mM), and ethylene glycol tetraacetic acid (EGTA; 500 microM) all had no effects on the changes in cell proliferation and DNA fragmentation induced by cerulein. The data suggest that supraphysiologic concentrations of cerulein rapidly induce apoptosis in AR4-2J cells and only later inhibit cell proliferation. These effects are mediated by CCK-A receptors. Cerulein-induced apoptosis may involve the induction of wild-type p53 or glutathione depletion or both.