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Primary and secondary amines selectively react with the lactone moiety of γ-valerolactone oxide (GVLO). Several primary amines afforded the resulting epoxyamides with an intact epoxy group. In some cases addition of two equivalents of amine resulted in additional epoxide opening to give α,γ-dihydroxy-ß-amino-amides. The selective lactone-opening in GVLO was further corroborated by DFT-studies.
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Industrially relevant intermediates such as malonic acid, malonates and 3-oxopropionates can be easily accessed by ozonolysis of α-angelica lactone, derived from the platform chemical levulinic acid. The roles of the solvent and of the quenching conditions are of key importance for the outcome of the reaction.
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4-Butirolactona/análogos & derivados , Malonatos/química , Ozônio/química , 4-Butirolactona/química , Malonatos/síntese química , Estrutura MolecularRESUMO
As the production volume of polymers increases, so does the amount of plastic waste. Plastic recycling is one of the concepts to address in this issue. Unfortunately, only a small fraction of plastic waste is recycled. Even with the development of polymers for closed loop recycling that can be in theory reprocessed infinitely the inherent dilemma is that because of collection, cleaning and separation processes the obtained materials simply are not cost competitive with virgin materials. Chemical upcycling, the conversion of polymers to higher valuable products, either polymeric or monomeric, could mitigate this issue. In the following article, we highlight recent examples in this young but fast-growing field. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.
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Novel polyester polyols were prepared in high yields from biobased 1,4-pentanediol catalyzed by non-toxic phosphoric acid without using a solvent. These oligomers are terminated with hydroxyl groups and have low residual acid content, making them suitable for use in adhesives by polyurethane formation. The thermal behavior of the polyols was studied by differential scanning calorimetry, and tensile testing was performed on the derived polyurethanes. The results were compared with those of polyurethanes obtained with fossil-based 1,4-butanediol polyester polyols. Surprisingly, it was found that a crystalline polyester was obtained when aliphatic long-chain diacids (>C12 ) were used as the diacid building block. The low melting point of the C12 diacid-based material allows the development of biobased shape-memory polymers with very low switching temperatures (<0 °C), an effect that has not yet been reported for a material based on a simple binary polyester. This might find application as thermosensitive adhesives in the packaging of temperature-sensitive goods such as pharmaceuticals. Furthermore, these results indicate that, although 1,4-pentanediol cannot be regarded as a direct substitute for 1,4-butanediol, its novel structure expands the toolbox of the adhesives, coatings, or sealants formulators.
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The amount of plastic waste is continuously increasing. Besides conventional recycling, one solution to deal with this problem could be to use this waste as a resource for novel materials. In this study, polyesters are hydrogenated to give polyether polyols by using in situ-generated Ru-Triphos catalysts in combination with Lewis acids. The choice of Lewis acid and its concentration relative to the ruthenium catalyst are found to determine the selectivity of the reaction. Monitoring of the molecular weight during the reaction confirms a sequential mechanism in which the diols that are formed by hydrogenation are etherified to the polyethers. To probe the applicability of this tandem hydrogenation etherification approach, a range of polyester substrates is investigated. The oligoether products that form in these reactions have the chain lengths that are appropriate for application in the adhesives and coatings industries. This strategy makes polyether polyols accessible that are otherwise difficult to obtain from conventional fossil-based feedstocks.
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BACKGROUND: Photodynamic therapy (PDT) is a palliative treatment for malignant biliary obstruction. OBJECTIVE: The objective of this article is to assess the feasibility and safety of this technique. METHODS: In this nationwide, retrospective study of prospectively collected clinical data, all patients treated with PDT using polyhematoporphyrin in Austria from March 2004 to May 2013 were included. Feasibility, adverse events, stent patency and mortality rates were investigated. RESULTS: Eighty-eight patients (54 male, 34 female, median age 69 years) underwent 150 PDT procedures at seven Austrian referral centers for biliary endoscopy. The predominant underlying disease was Klatskin tumor (79/88). All PDT procedures were feasible without technical issues. Cholangitis was the most frequent adverse event (21/88). Stent patency was 246 days (95% CI 203-289) median and was significantly longer for metal than for plastic stents (269 vs. 62 days, p < 0.01). The median survival was 12.4 months (95% CI 9.7-14.9 m) calculated from first PDT and 15.6 months (95% CI 12.3-18.7 m) calculated from initial diagnosis. In patients suffering from biliary tract cancer, Cox regression revealed the number of PDT treatment sessions as the only independent predictor of survival at a multivariate analysis (p = 0.048). CONCLUSION: PDT using polyhematoporphyrin was feasible and safe in this nationwide analysis. Survival data suggest a benefit of PDT in this unselected real-life patient population. Prospective trials comparing PDT to other palliative treatments will help to define its role in the management of malignant biliary obstruction. The study is registered at ClinicalTrials.gov number: NCT02504957.
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Daclatasvir (DCV) is a potent, pangenotypic nonstructural protein 5A inhibitor with demonstrated antiviral efficacy when combined with sofosbuvir (SOF) or simeprevir (SMV) with or without ribavirin (RBV) in patients with chronic hepatitis C virus (HCV) infection. Herein, we report efficacy and safety data for DCV-based all-oral antiviral therapy in liver transplantation (LT) recipients with severe recurrent HCV. DCV at 60 mg/day was administered for up to 24 weeks as part of a compassionate use protocol. The study included 97 LT recipients with a mean age of 59.3 ± 8.2 years; 93% had genotype 1 HCV and 31% had biopsy-proven cirrhosis between the time of LT and the initiation of DCV. The mean Model for End-Stage Liver Disease (MELD) score was 13.0 ± 6.0, and the proportion with Child-Turcotte-Pugh (CTP) A/B/C was 51%/31%/12%, respectively. Mean HCV RNA at DCV initiation was 14.3 × 6 log10 IU/mL, and 37% had severe cholestatic HCV infection. Antiviral regimens were selected by the local investigator and included DCV+SOF (n = 77), DCV+SMV (n = 18), and DCV+SMV+SOF (n = 2); 35% overall received RBV. At the end of treatment (EOT) and 12 weeks after EOT, 88 (91%) and 84 (87%) patients, respectively, were HCV RNA negative or had levels <43 IU/mL. CTP and MELD scores significantly improved between DCV-based treatment initiation and last contact. Three virological breakthroughs and 2 relapses occurred in patients treated with DCV+SMV with or without RBV. None of the 8 patient deaths (6 during and 2 after therapy) were attributed to therapy. In conclusion, DCV-based all-oral antiviral therapy was well tolerated and resulted in a high sustained virological response in LT recipients with severe recurrent HCV infection. Most treated patients experienced stabilization or improvement in their clinical status.
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Antivirais/uso terapêutico , Hepatite C Crônica/tratamento farmacológico , Imidazóis/uso terapêutico , Simeprevir/uso terapêutico , Sofosbuvir/uso terapêutico , Idoso , Antivirais/administração & dosagem , Antivirais/efeitos adversos , Carbamatos , Ensaios de Uso Compassivo , Quimioterapia Combinada/métodos , Feminino , Genótipo , Hepacivirus/genética , Hepacivirus/isolamento & purificação , Hepatite C Crônica/complicações , Hepatite C Crônica/virologia , Humanos , Imidazóis/administração & dosagem , Imidazóis/efeitos adversos , Cirrose Hepática/etiologia , Cirrose Hepática/patologia , Hepatopatias/cirurgia , Transplante de Fígado/efeitos adversos , Masculino , Pessoa de Meia-Idade , Pirrolidinas , Recidiva , Estudos Retrospectivos , Ribavirina/administração & dosagem , Ribavirina/efeitos adversos , Ribavirina/uso terapêutico , Simeprevir/administração & dosagem , Simeprevir/efeitos adversos , Sofosbuvir/administração & dosagem , Sofosbuvir/efeitos adversos , Resultado do Tratamento , Valina/análogos & derivadosRESUMO
BACKGROUND: Dieulafoy lesions consist of aberrant submucosal arteries, which can cause severe GI bleeding. The predominant location of Dieulafoy lesions is the upper GI tract. OBJECTIVE: To our best knowledge, this is the first systematic study on the frequency of bleeding from Dieulafoy lesions in the small bowel and the efficacy of enteroscopic therapy regarding primary hemostasis and long-term follow-up. DESIGN: Multicenter, retrospective, observational study. SETTING: Nine Austrian centers doing double-balloon enteroscopy or single-balloon enteroscopy. PATIENTS: This study involved 284 consecutive patients who were referred for double-balloon enteroscopy or single-balloon enteroscopy because of suspicion of mid-GI bleeding. INTERVENTION: A total of 317 double-balloon enteroscopy and 78 single-balloon enteroscopy procedures were performed in 284 patients with suspected mid-GI bleeding. MAIN OUTCOME MEASUREMENTS: Demographic, clinical, procedural, and outcome data were collected. RESULTS: A Dieulafoy lesion in the small bowel was identified as the source of mid-GI bleeding in 3.5% of patients, with a mean of 1.5 enteroscopy sessions required per diagnosis. In 9 cases the Dieulafoy lesion was found by enteroscopy from an oral approach, and in 1 patient the lesion was found by an anal approach. In all patients primary endoscopic hemostasis was successful. Eight of 10 patients were free from rebleeding episodes (median follow-up 14.5 months, interquartile range 10.0-17.5 months). In 2 of 10 patients, rebleeding occurred, and a surgical intervention was necessary. LIMITATIONS: Retrospective study. CONCLUSION: Bleeding from Dieulafoy lesions of the small bowel seems to occur more frequently than previously estimated. Most of these lesions are located in the proximal jejunum and can be managed successfully by enteroscopy. After successful endoscopic hemostasis, rebleeding episodes occur in only 20% of patients.
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Artérias/patologia , Hemorragia Gastrointestinal/terapia , Hemostase Endoscópica , Idoso , Idoso de 80 Anos ou mais , Coagulação com Plasma de Argônio , Enteroscopia de Duplo Balão , Epinefrina/uso terapêutico , Feminino , Seguimentos , Hemorragia Gastrointestinal/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva , Estudos Retrospectivos , Instrumentos Cirúrgicos , Resultado do Tratamento , Vasoconstritores/uso terapêuticoRESUMO
BACKGROUND: Percutaneous endoscopic gastrostomy (PEG) is the method of choice for long- term artificial enteral feeding. Standardized wound management such as daily dressing changes and local disinfection of the exit site helps to keep complication rates low. New bacteriostatic glycogel wound dressing has not yet been tested. We compared glycogel dressing to the usual method of wound aftercare with regard to wound infections. METHODS: The standard wound management was compared to glycogel dressing. 100 consecutive patients were investigated in a prospective randomized trial from Aug. 2004 to Jan. 2006 regarding wound infections. We also compared indications for PEG placement, complications other than wound infection, and mortality. The exit site was examined and scored daily using a specific wound scoring system. After 30 days, the patients were followed up by phone calls to determine if any infection had occurred after discharge. RESULTS: During our study, 98 out of 100 patients had a successful PEG procedure performed. Out of these 98 patients, 48 patients received standard wound dressing care and 50 patients used glycogel dressing. The indications for PEG placement were not significantly different between the two groups. A total of 88% of patients (n = 42) with standard wound care had no relevant infection (50%, n = 24 with score 0 or 1; 38%, n = 18 had score 2), 10% (n = 5) presented with serious local infection (score 3) and one patient (2%) had severe infection necessitating PEG removal (score 4). In the group using glycogel dressing, 88% of the patients (n = 44) did not show any relevant sign of infection (54%, n = 27 with score 0 or 1; 34%, n = 17 had score 2), 8% (n = 4) had serious local infection (score 3), 2% (n = 1) had severe infection (score 4) and 2% (n = 1) were lost to follow up. CONCLUSION: Regarding wound infection rates after PEG placement, glycogel wound dressing was found to be as effective as standard wound dressing. Thus, omitting daily changes of regular wound dressings by using glycogel dressing instead may be advantageous for patients and generally help to decrease overall cost.
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Antibacterianos/administração & dosagem , Curativos Hidrocoloides , Nutrição Enteral , Gastrostomia , Infecção da Ferida Cirúrgica/prevenção & controle , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibioticoprofilaxia , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Infecção da Ferida Cirúrgica/epidemiologiaRESUMO
Mutualists can affect many life history traits of their partners, but it is unclear how this translates into population dynamics of the latter. Ant-aphid associations are ideal for studying this question, as ants affect aphids, both positively (e.g., protection against natural enemies) and negatively (e.g., reduction of potential growth rates). The unresolved question is whether these effects, which have been observed at the level of individuals and under controlled environmental conditions, have consequences at the population level. On estimating aerial aphid populations by using weekly suction trap data spanning up to 22 years from different locations in France, we show that in ant-attended aphid species long-distance dispersal occurs significantly later, but that the year-to-year changes in the peak number of migrants are not significantly lower than for non-attended aphids. Host alternation had the same retarding effect on dispersal as ant attendance. We discuss the delay in the timing of dispersal in ant-attended aphids, and potential costs that arise in mutualistic systems.
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Migração Animal/fisiologia , Formigas/fisiologia , Afídeos/fisiologia , Animais , Demografia , Ecossistema , França , Fatores de TempoRESUMO
OBJECTIVE: Percutaneous endoscopic gastrostomy (PEG) is the method of choice in maintaining enteral nutrition in patients with swallowing and nutritional disorders of different etiology. The aim of this study was to assess the long-term outcome of patients following placement of a PEG. MATERIAL AND METHODS: All patients who received a PEG between October 1999 and September 2000 were included in this prospective study. Long-term function, replacement or removal of the PEG, complications and survival of the patients were analyzed in group A (younger than 75 years) and group B (75 years or older). RESULTS: The indications for PEG placement in group A (54 patients, mean age 54.5 years) were neurological (66.7%) and malignant (31.5%) disorders, whereas in group B (40 patients, mean age 81 years) the indications were predominantly neurological diseases (87.5%). The majority of patients (91 of 94 patients; 96.8%) could be followed long term or until death. In group A, 46 patients (85.2%) had uncomplicated long-term function of their PEG and interventions were necessary in only 8 patients. Removal of the PEG was possible during the course in 17 patients (31.5%). In group B, uncomplicated long-term function was observed in 34 patients (85%) and interventions were required in only 6 patients. Removal of the PEG was not possible in group B. Survival rates for 1-, 2- and 5 years in group A were 73.9%, 61.8% and 43.9%, respectively, and in group B 41.4%, 31.9% and 15.9%, respectively; the difference was statistically significant (p=0.002). CONCLUSIONS: Excellent long-term function of PEG was seen in this study of 94 consecutive patients, and interventions were necessary only in a minority of patients. The prognosis for older patients was worse; however, the 2-year survival rate of 32% justified the PEG insertion.
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Endoscopia Gastrointestinal , Gastrostomia/métodos , Desnutrição/cirurgia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Áustria/epidemiologia , Criança , Pré-Escolar , Feminino , Seguimentos , Humanos , Lactente , Masculino , Desnutrição/etiologia , Desnutrição/mortalidade , Pessoa de Meia-Idade , Estudos Prospectivos , Taxa de Sobrevida , Fatores de Tempo , Resultado do TratamentoRESUMO
BACKGROUND: Biliary disease frequently occurs in the elderly, but there are limited data on ERCP in the elderly population. PATIENTS: A total of 502 patients (group A, 97; group B, 405) underwent 724 ERCP procedures. MAIN OUTCOME MEASUREMENTS: All consecutive ERCPs performed between 2000 and 2002 at a single center were retrospectively reviewed for patients >/=80 years old (group A) and patients <80 years old (group B) to evaluate endoscopic findings, interventions, complications, and mortality related to complications. RESULTS: The number of important chronic concomitant diseases was significantly higher in the older group (average per patient 1.08 vs 0.57, P < .001). Successful cannulation was achieved in 88% in group A versus 86% in group B, and endoscopic sphincterotomy was performed in 63.2% versus 51.4%. Periampullary diverticulum was found significantly more often in patients of group A (39.2%) than of group B (14.1%, P < .001). Stents were used in 24.1% of ERCP procedures in group A and in 22.9% in group B. There was no significant difference in the complication rate between group A (6.8%) and group B (5.1%) and in early mortality (1.03% vs 0.25%), respectively. CONCLUSION: ERCP is a safe and effective intervention in the elderly because complication and early mortality rates are comparable to those of younger patients, although comorbidity is significantly higher.
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Doenças dos Ductos Biliares/diagnóstico , Doenças dos Ductos Biliares/terapia , Colangiopancreatografia Retrógrada Endoscópica/métodos , Litotripsia/métodos , Esfinterotomia Endoscópica/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças dos Ductos Biliares/mortalidade , Criança , Diagnóstico Diferencial , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Taxa de Sobrevida , Resultado do TratamentoRESUMO
The hemlock woolly adelgid (HWA, Adelges tsugae Annand) is currently causing a severe decline in vitality and survival of eastern hemlock in North American forests. We analyzed the effects of light HWA infestation on vertical energy and nutrient fluxes from the canopy to the forest floor. Canopy throughfall, litter lysimeters, and laboratory litter microcosms were used to examine the effects of HWA-affected and unaffected throughfall on litter type, leachate, and litter chemistry. Early in the season adelgid infestation caused higher dissolved organic carbon (DOC; +24.6%), dissolved organic nitrogen (DON; +28.5%), and K (+39.3%) fluxes and lower inorganic nitrogen fluxes (-39.8%) in throughfall and in adjacent litter solutions collected beneath infested compared to uninfested trees. Needle litter collected beneath uninfested hemlock had significantly lower N concentrations compared to needles collected beneath infested trees, while no difference in N concentrations was found in birch litter. Bacteria were significantly more abundant on hemlock and birch litter beneath infested trees, while yeasts and filamentous fungi showed no consistent response to HWA throughfall. Litter microcosms showed that less DOC was leaching from birch than from hemlock needles when exposed to HWA throughfall. Overall, NH4-N and DON leachate concentrations were higher from birch than from hemlock litter. Thus, HWA-affected throughfall leads to qualitative and quantitative differences in nitrogen export from the litter layer. The N concentration of hemlock litter did not change with time, but the N concentration in birch litter increased significantly during the course of the experiment, especially when HWA-affected throughfall was applied. We suggest a nonlinear conceptual model for the temporal and vertical transition of energy and nutrient fluxes relative to progressing HWA infestation from a pure hemlock to a birch/maple-dominated forest. Progressive needle loss and changes in needle chemistry are likely to produce a humped-shaped DOC curve, while N fluxes initially decrease as infestation continues but rise eventually with hemlock decline and immigration of hardwood species. These findings suggest that it is necessary to understand the biology and specific physiological/trophic effects of exotic pests on their hosts and associated ecosystem processes in order to decipher the temporal dynamics, direction of change, and functional consequences.
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Ecossistema , Hemípteros/fisiologia , Árvores/fisiologia , Árvores/parasitologia , Tsuga/parasitologia , Animais , Cicloexanos/metabolismo , Metabolismo Energético , Nitrogênio/metabolismo , Estações do AnoRESUMO
AIM: To investigate the prevalence of colorectal cancer in geriatric patients undergoing endoscopy and to analyze their outcome. METHODS: All consecutive patients older than 80 years who underwent lower gastrointestinal endoscopy between January 1995 and December 2002 at our institution were included. Patients with endoscopic diagnosis of colorectal cancer were evaluated with respect to indication, localization and stage of cancer, therapeutic consequences, and survival. RESULTS: Colorectal cancer was diagnosed in 88 patients (6% of all endoscopies, 55 women and 33 men, mean age 85.2 years). Frequent indications were lower gastrointestinal bleeding (25%), anemia (24%) or sonographic suspicion of tumor (10%). Localization of cancer was predominantly the sigmoid colon (27%), the rectum (26%), and the ascending colon (20%). Stage Dukes A was rare (1%), but Dukes D was diagnosed in 22% of cases. Curative surgery was performed in 54 patients (61.4%), in the remaining 34 patients (38.6%) surgical treatment was not feasible due to malnutrition and asthenia or cardiopulmonary comorbidity (15 patients), distant metastases (11 patients) or refusal of operation (8 patients). Patients undergoing surgery had a very low in-hospital mortality rate (2%). Operated patients had a one-year and three-year survival rate of 88% and 49%, and the survival rates for non-operated patients amounted to 46% and 13% respectively. CONCLUSION: Nearly two-thirds of 88 geriatric patients with endoscopic diagnosis of colorectal cancer underwent successful surgery at a very low perioperative mortality rate, resulting in significantly higher survival rates. Hence, the clinical relevance of lower gastrointestinal endoscopy and oncologic surgery in geriatric patients is demonstrated.
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Colonoscopia , Neoplasias Colorretais/patologia , Neoplasias Colorretais/cirurgia , Idoso , Idoso de 80 Anos ou mais , Neoplasias Colorretais/mortalidade , Feminino , Humanos , Masculino , Estadiamento de Neoplasias , Estudos Retrospectivos , Análise de Sobrevida , Resultado do TratamentoRESUMO
Ants are a major environmental factor for many insect species. For example, aphids and lycaenids have evolved an array of associations with ants ranging from obligate myrmecophily to the avoidance of contact. Here we (1) analyze the predictive power of different ecological and morphological traits for explaining the strength of the association between ants and aphids/lycaenids and (2) contrast different taxonomic levels with respect to the variance explained by ant attendance. Data come from a literature survey including 112 species of aphids and 103 species of lycaenids from Europe. For aphids, feeding on woody plant parts is positively associated with ant attendance, while a high degree of mobility, feeding in isolation, and the possession of wings in the adult stage are negatively associated with ant attendance. In lycaenids, feeding on inflorescences and feeding on Fabaceae host plants is closely associated with ant attendance, while living in forests bears a smaller likelihood to establish mutualistic relationships. Body size always appeared to be a poor predictor for the degree of ant attendance. Overall, in both insect groups less than 10% of the variation in the ecological traits recorded is explained by the different modes of ant association. When decomposing the variance in traits explained by ant attendance at different taxonomic levels, aphids and lycaenids show contrasting results. In aphids, most variance in the degree of ant attendance is explained at the subfamily level and least at the species level. The opposite is true for lycaenids, where most variance is explained at the lowest taxonomic level. Possible mechanisms explaining these different patterns of associations with ants are suggested.
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Formigas/anatomia & histologia , Afídeos/anatomia & histologia , Plantas Comestíveis , Adaptação Fisiológica , Animais , Formigas/fisiologia , Afídeos/fisiologia , Constituição Corporal , Classificação , Ecossistema , Feminino , Masculino , Dinâmica Populacional , ÁrvoresRESUMO
BACKGROUND: Percutaneous endoscopic gastrostomy (PEG) plays an important role in maintaining enteral nutrition in patients with swallowing disorders of different etiologies. The aim of our study was to record indications and complications of PEG-placement in a one-year period. METHODS: All patients were investigated prospectively regarding indications, wound infections, other complications and mortality between 1999-10-01 and 2000-09-30. The exit site was examined daily, after 30 days a follow-up by telephone was carried out. RESULTS: The PEG-procedure was performed in 93 patients, one patient received a percutaneous endoscopic jejunostomy. The mean age of the patients was 65.4 years (range 7 months--92 years). The most frequent indications were neurological diseases (n = 61, 65%). 21 patients had a PEG-placement because of malignancies (22%), 9 patients following brain injury (10%) and 3 patients (3%) due to other benign swallowing disorders. 63 patients (67%) had no complications, 28 patients (30%) had wound infections, and in two patients hemorrhage was observed (small hematoma requiring no further intervention). One patient had laparotomy because of suspected perforation--however, laparotomy was negative. In 7 patients (7%) wound infections (n = 28) were mild and needed only local or no therapy. In 18 patients (19%) we found a relevant infection that required systemic antibiotic therapy. 2 patients had serious local infections that caused further interventions. One patient died from sepsis caused by wound infection. Patients receiving antibiotic therapy at the time of PEG-placement suffered from wound infections in 25%. Patients with malignant diseases more often had wound infections. 8 patients died after 7 days and 19 patients after 30 days (8% and 19%, respectively) from their underlying disease. CONCLUSIONS: PEG is regarded as a small intervention with low morbidity and mortality. However, our analysis of daily practice shows a remarkable rate of complications. The high mortality in our study reflects the seriousness of the comorbidities. Antibiotic therapy failed to prevent wound infection in 25% of our patients.
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Gastrostomia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibioticoprofilaxia , Lesões Encefálicas/complicações , Criança , Pré-Escolar , Transtornos de Deglutição/etiologia , Transtornos de Deglutição/terapia , Endoscopia , Nutrição Enteral , Seguimentos , Gastrostomia/efeitos adversos , Gastrostomia/métodos , Hemorragia/etiologia , Hemorragia/terapia , Humanos , Lactente , Pessoa de Meia-Idade , Neoplasias/complicações , Doenças do Sistema Nervoso/complicações , Estudos Prospectivos , Fatores de Tempo , Infecção dos Ferimentos/etiologia , Infecção dos Ferimentos/prevenção & controle , Infecção dos Ferimentos/terapiaRESUMO
The community composition of epiphytic heterotrophic bacteria on leaves of beech and oak, which were either damaged by lepidopterous larvae or remained undamaged, was investigated. In addition, the ability of these bacteria to utilize inorganic nitrogen was studied. The bacteria were isolated on nutrient agar and systematically identified with biochemical and physiological tests. Rarefaction plots and the Shannon-Wiener function revealed that species diversity was significantly higher on leaves of damaged beech compared to undamaged leaves, but no differences were found on leaves of oak. The portion of bacterial isolates showing a strong response to ammonia and nitrate was significantly larger on leaves of oak than on those of beech. Furthermore, significantly more isolates with a high capability to assimilate both nitrogen compounds were found on leaves attacked by the folivorous larvae compared to those not attacked on oak. It is suggested that the changes in the microbial community in response to folivorous insects might affect the extent of nutrient cycling exceeding eventually the scale of a leaf.
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Bactérias/isolamento & purificação , Fagus/microbiologia , Lepidópteros/microbiologia , Folhas de Planta/microbiologia , Quercus/microbiologia , Amônia/metabolismo , Animais , Bactérias/classificação , Meios de Cultura , Ecossistema , Larva/microbiologia , Lepidópteros/crescimento & desenvolvimento , Nitratos/metabolismoRESUMO
Phytophagous insects can have severe impacts on forested ecosystems in outbreak situations but their contribution to flows of energy and matter is otherwise not so well known. Identifying the role of phytophagous insects in forested ecosystems is partly hindered by the difficulty of combining results from population and community ecology with those from ecosystem ecology. In our study we compared the effects of aphids and leaf-feeding lepidopterous larvae on the epiphytic micro-organisms in the canopies of spruce, beech and oak, and on the vertical flow of energy and nutrients from the canopies down to the forest floor. We particularly searched for patterns resulting from endemic herbivory rather than outbreak situations. Excreta of lepidopterous larvae and aphids promoted the growth of epiphytic micro-organisms (bacteria, yeasts, filamentous fungi) on needles and leaves, which suggests that micro-organisms were energy limited. Leachates from needles and leaves of infested trees contained higher concentrations of dissolved organic C and lower concentrations of NH4-N and NO3-N, relative to uninfested trees. The seasonal abundance of herbivores and micro-organisms significantly affected the dynamics of throughfall chemistry; for instance, concentrations of inorganic N were lower underneath infested than uninfested trees during June and July. There was little difference between the chemistry of soil solutions collected from the forest floor beneath infested and uninfested trees. Thus, under moderate to low levels of infestation the effects of above-ground herbivory seems to be obscured in the soil through buffering biological processes.
RESUMO
Aphids of the genus Cinara, feeding on Norway spruce, excrete copious amounts of honeydew, a carbon-rich waste product, which accumulates locally on needles and twigs. We investigated the role of honeydew as a potential source of energy which might promote the growth of micro-organisms in the phyllosphere of conifer trees. To approach this question, we followed the population dynamics of Cinara spp. in a natural forest stand over two seasons. We also studied the amounts of honeydew produced by individual aphids and identified potential parameters which might influence honeydew production. Finally, we determined the growth of micro-organisms on infested and uninfested needles of Norway spruce during the growing season. Confined to Picea abies, the investigated Cinara species only became abundant in midsummer, when needles and shoots were expanding. The populations showed only a single peak in abundance, the timing and magnitude of which may vary from year to year due to weather conditions, changes in plant quality in a yearly cycle or the impact of natural enemies. The amount of honeydew produced by individual aphids was dependent on the developmental stage of the aphid, the nutritional supply of its host plant and on the developmental state of the Norway spruce (e.g. bud burst, end of shoot extension). The presence of honeydew significantly increased the growth of bacteria, yeast and filamentous fungi on the surface of needles and there was a pronounced seasonal trend, with the highest abundance in midsummer correlating with the period of peak aphid abundance. Taken together, these findings indicate that aphids have an influence on microbial ecology in the phyllosphere of trees. The implication of our study, from interactions at the population level to effects and potential consequences for C and N fluxes at the level of forest ecosystems, is discussed.
RESUMO
The need to allocate a limited amount of energy between different life-history traits is a fundamental assumption in life-history theory. However, it has often turned out to be extremely difficult to measure the competing processes that contribute to costs or benefits for individual organisms. The present investigation begins by analysing how an aphid clonal lineage adapts its reproductive investment to moderate changes in host plant quality (e.g. during the life cycle of its host). Using Centaurea jacea and Uroleucon jaceae as a model plantaphid system, I show that reproductive investment can be far more complex than indicated by dry or wet mass of the gonads alone. The number of embryos of a particular size class or developmental state present in the reproductive system of an aphid is highly flexible and is influenced by the quality of the host plant. Next, the effects of a particular reproductive investment on survival during periods of food deprivation are analysed for aphids originating from host-plants of different qualities. When food stress is severe the ability to rapidly resorb and reallocate resources committed to offspring is important for survival. However, this ability is limited. I argue that, in periods of food stress, young, unsclerotized embryos might serve as a kind of energy buffer similar to a fat body and are therefore not relevant to cost-benefit calculations. However, embryos that are beginning to sclerotize within the ovarioles are not available for resorption and resource reallocation. They compete for nutrients with their mother and contribute to costs. Therefore, it is suggested that the reproductive investment of an aphid should not be equated with reproductive costs in a general al way. The dynamics of adaptive resource allocation and resorption are a key feature of an aphid's life history, and the implications for life-history theory are discussed.