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Biomedical subjects

R Aerts

Publications and source records attributed to R Aerts.

At least 19 recordsLinked to original sources
PubMed2006

Determinants of complications in pancreaticoduodenectomy.

AIMS: The factors determining complications after pancreaticoduodenectomy (PD) have not yet been identified clearly. This retrospective study examined, using reproducible classification systems, the type and severity of complications as well as the factors to predict them. METHODS: Between 1998 and 2005 PD was performed in 351 consecutive patients with peri-ampullary tumours. Logistic regression models were used in univariate as well as in corrected, multivariate analyses in order to identify the optimally combined factors related to the occurrence of post-operative complications. RESULTS: Post-operative complication rate was 50.7%, mortality 3.1% and re-operation rate 7.1%. Pancreatic fistula (12%) was responsible for higher mortality (9.5%; p=0.011) and re-operation (30.9%; p<0.001) rates. Hospital length of stay (LOS) was (p<0.001) longer for patients with post-operative complications (median 21.5 (range 1-128) vs. 14 (7-42) days) or pancreatic fistula (28.5 (8-128) vs. 17 (1-63) days), and related to the severity of complications. Surgeon (Odds ratio [OR] 2.03; confidence interval [CI] 1.20-3.41; p=0.008), male gender (OR 1.72; CI 1.05-2.81; p=0.032), and pre-operative hyperbilirubinaemia (OR 1.04; CI 1.001-1.08; p=0.046) were independent risk factors for post-operative complications. Neither prophylactic octreotide nor pre-operative biliary drainage improved post-operative outcome. CONCLUSION: Surgeon, male gender, and pre-operative hyperbilirubinaemia determine complication rate following PD. Pancreatic fistula is the most common complication and is associated with increased mortality, re-operation rate and LOS.

Adult↗
PubMed2006

Laparoscopic liver resection using radiofrequency coagulation.

BACKGROUND: The use of radiofrequency (RF) energy has been described to perform open liver resection safely and with minimal blood loss. Yet no data are available on the potential contribution of RF energy to the limitation of intraoperative blood loss during laparoscopic liver resection (LLR). The aim of this prospective, nonrandomized study was to investigate the potential contribution of RF energy to the limitation of intraoperative blood loss in patients undergoing LLR. METHODS: Forty-five patients [male/female ratio 22/23, age 57 years (26-80)] underwent LLR. Eleven benign and 47 malignant lesions (mostly colorectal metastases) were resected. Median number [1 (1-3)] and maximum diameter [40 mm (8-170)] of tumors as well as median tumor free margins [10 mm (1-30)] were comparable in patients undergoing LLR with (20 patients) or without (25 patients) RF-assistance. Thirty-eight minor (< or = 2 segments) and 9 major (> 3 segments) resections were performed. Eighteen patients simultaneously underwent additional surgery. RESULTS: No mortality occurred. Median intraoperative blood loss was 200 (5-4000) ml and was similar in patients undergoing LLR with or without RF-assistance. The type of surgical procedure was a determinant for the amount of intraoperative blood loss (p = 0.0002). Significant bleeding occurred from large hepatic vessels at major resections. Median operation time was 115 (45-360) minutes. RF-assistance didn't seem to reduce perioperative morbidity. CONCLUSIONS: LLR can be performed with minimal intraoperative blood loss, which is determined by the type of hepatectomy. Significant intraoperative bleeding occurs from large hepatic vessels during major resections. RF-assisted parenchymal transection in LLR doesn't seem to reduce blood loss, operation time, or perioperative morbidity.

Adult↗
PubMed2006

Climate change has only a minor impact on nutrient resorption parameters in a high-latitude peatland.

Nutrient resorption from senescing plant tissues is an important determinant of the fitness of plant populations in nutrient-poor ecosystems, because it makes plants less dependent on current nutrient uptake. Moreover, it can have significant "afterlife" effects through its impact on litter chemistry and litter decomposability. Little is known about the effects of climate change on nutrient resorption. We studied the effects of climate change treatments (including winter snow addition, and spring and/or summer warming) on nutrient resorption of four dominant species in a nutrient-poor subarctic peatland. These species were Betula nana (woody deciduous), Vaccinium uliginosum (woody deciduous), Calamagrostis lapponica (graminoid) and Rubus chamaemorus (forb). After five years of treatments both mature and senesced leaf N concentrations showed a small but significant overall reduction in response to the climate treatments. However, the effects were species-specific. For example, in the controls the N concentration in senesced leaves of Calamagrostis (3.0+/-0.2 mg N g(-1)) was about four times lower than for Rubus (11.2+/-0.2 mg N g(-1)). There were no significant treatment effects on N resorption efficiency (% of the N pool in mature leaves that is resorbed during senescence). The nitrogen resorption efficiency of Calamagrostis (about 80%) was higher than in the other three species (about 60%). Thus, climate change has only a minor impact on nutrient resorption parameters. However, given the substantial interspecific differences in these parameters, substantial changes in plant-soil feedbacks may be expected as a result of the observed changes in the species composition of high-latitude vegetation. These changes are species-specific and thus difficult to predict.

Analysis of Variance↗
PubMed2006

The clinicopathological and prognostic relevance of cytokeratin 7 and 19 expression in hepatocellular carcinoma. A possible progenitor cell origin.

AIMS: Cytokeratin (CK) 7 and CK19 expression, present in hepatic progenitor cells (HPCs) and in cholangiocytes but not in normal hepatocytes, has been reported in some hepatocellular carcinomas (HCCs); however, the incidence and relevance of this expression in HCC in Caucasians is not known. Therefore, our aim was to study the occurrence and clinicopathological characteristics of HCC expressing CK7 and/or CK19 in 109 Caucasian patients. METHODS AND RESULTS: The expression of hepatocellular differentiation markers (Hepar, canalicular polyclonal carcinoembryonic antigen), biliary/progenitor cell markers (CK7, CK19), alpha-fetoprotein (AFP), p53 and beta-catenin in HCC was semiquantitatively assessed by immunohistochemistry. Of 109 HCCs, 78 were CK7-/CK19- (72%), 13 CK7+/CK19- (12%), seven CK7-/CK19+ (6%), 11 CK7+/CK19+ (10%). CK19 expression was significantly associated with elevated serum AFP (400 ng/ml) (P = 0.023), tumour AFP expression (P < 0.0001), presence in serum of anti-hepatitis B core (P = 0.016), less fibrosis in non-neoplastic parenchyma (P = 0.009) and less nuclear beta-catenin expression (P = 0.021). CK7 expression was significantly associated with elevated serum bilirubin (> 2 mg/dl) (P = 0.0005) and less nuclear beta-catenin expression (P = 0.003). HCC expressing CK19 had a higher rate of recurrence (P = 0.009, hazard ratio 12.5, n = 31) after liver transplantation compared with CK19- tumours. CONCLUSIONS: In our series, 28% of HCCs contained cells expressing CK7 and/or CK19. They potentially derive from HPCs. The higher recurrence rate of CK19+ HCC after transplantation suggests a worse prognosis for these HCCs compared with CK19- HCC.

Adult↗
PubMed2005

Foliar pH as a new plant trait: can it explain variation in foliar chemistry and carbon cycling processes among subarctic plant species and types?

Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However, foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or ecosystem traits and processes.

Animals↗
PubMed2005

Nitrogen supply differentially affects litter decomposition rates and nitrogen dynamics of sub-arctic bog species.

High-latitude peatlands are important soil carbon sinks. In these ecosystems, the mineralization of carbon and nitrogen are constrained by low temperatures and low nutrient concentrations in plant litter and soil organic matter. Global warming is predicted to increase soil N availability for plants at high-latitude sites. We applied N fertilizer as an experimental analogue for this increase. In a three-year field experiment we studied N fertilization effects on leaf litter decomposition and N dynamics of the four dominant plant species (comprising >75% of total aboveground biomass) in a sub-arctic bog in northern Sweden. The species were Empetrum nigrum (evergreen shrub), Eriophorum vaginatum (graminoid), Betula nana (deciduous shrub) and Rubus chamaemorus (perennial forb). In the controls, litter mass loss rates increased in the order: Empetrum<Eriophorum<Betula<Rubus. Increased N availability had variable, species-specific effects: litter mass loss rates (expressed per unit litter mass) increased in Empetrum, did not change in Eriophorum and Betula and decreased in Rubus. In the leaf litter from the controls, we measured no or only slight net N mineralization even after three years. In the N-fertilized treatments we found strong net N immobilization, especially in Eriophorum and Betula. This suggests that, probably owing to substantial chemical and/or microbial immobilization, additional N supply does not increase the rate of N cycling for at least the first three years.

Arctic Regions↗
PubMed2005

The landsnail Cepaea nemoralis regulates internal Cd levels when fed on Cd-enriched stinging nettle (Urtica dioica) leaves at low, field-relevant concentrations.

We studied Cd accumulation in Cepaea nemoralis snails at low, but field-relevant Cd concentrations in the diet (Urtica dioica leaves). Six treatments of U. dioica plants were grown, resulting in leaf Cd concentrations between 0 and 2.6 microg g(-1) dw. Seven snails per treatment were fed for 38 days. Leaf Cd concentrations did not affect food consumption rates, and consequently Cd intake rates increased with increasing leaf concentrations. No differences were detected among treatments in the final soft tissue Cd concentrations and body burdens in the snails. Regression analyses showed no positive relationship between either snail Cd concentrations or body burdens and total Cd intake. This suggests a regulation of internal Cd concentrations at low food Cd concentrations. Our data suggest that Cd excretion via the mucus plays a substantial role in this regulation, in addition to Cd excretion via the faeces. Snail shells were no sinks for Cd.

Animals↗
PubMed2005

Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient.

We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r2 = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r2 = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r2 = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil.

Animals↗
PubMed2005

Liver transplantation using cavoportal transposition: an effective treatment in patients with complete splanchnic venous thrombosis.

Complete venous thrombosis of the splanchnic system remains a major challenge in liver transplantation surgery. Some of these patients have been treated successfully by multivisceral transplantation. Cavoportal transposition is another alternative to treat these patients. We reviewed our single-center experience with this technique. Five patients with operatively confirmed complete splanchnic thrombosis were transplanted with the cava portal transposition technique. All survived the procedure; 60% survived long term. This technique is a useful salvage procedure in moribund patients with diffuse portal thrombosis who would otherwise rapidly succumb.

Adult↗
PubMed2005

Liver transplantation using livers from septuagenarian and octogenarian donors: an underused strategy to reduce mortality on the waiting list.

Shortage of liver grafts is the only limiting factor for application of liver transplantation and causes an increasing mortality on the waiting list. Very old donors (>70 to 80 years old) are rarely referred to transplant centers because of the assumption that these livers will not work properly. Alternatively, transplant teams may be reluctant to use these very old livers due to the risk of poor posttransplant outcome. We reviewed our experience with seven liver transplantations using very old donor livers. We found that the results in terms of graft function and patient survival are adequate. Interestingly, the majority of these donors originated from a single referring donor unit (of more than 20 units who belong to our donor network) that systematically refers all brain-dead donors to the transplant center, independent of the age of the potential donor. This implies that many of these donors are left undetected in other units. In conclusion, very old donors should be referred to transplant centers since results of transplantation with these grafts are favorable.

Age Factors↗
PubMed2005

Is UV-B radiation affecting charophycean algae in shallow freshwater systems?

The objective of this study was to determine the effects of UV-B radiation on charophycean algae under natural conditions, since charophytes enhance water transparency in freshwater systems and levels of UV-B radiation have increased by ozone depletion. Potential and actual UV-B effects were studied by combining a glasshouse experiment in which plants were exposed to various levels of UV-B radiation and field measurements in two freshwater systems dominated by charophytes in the Netherlands. The glasshouse experiment showed that charophytes were sensitive to UV-B radiation. UV-B radiation negatively affected growth, while it increased levels of DNA damage in Chara aspera. Moreover, the charophytes did not seem to develop UV-B screens to protect against UV-B radiation since no increase in UV-B absorbing compounds was found. At field conditions, both spectroradiometrical measurements and DNA dosimeters showed that UV-B radiation was attenuated quickly in both freshwater systems, indicating that UV-B does not reach the submerged charophyte vegetation. However, specific conditions, like fluctuating water tables, may result in UV-B exposure to charophytes for certain periods annually.

Chara↗
PubMed2005

Case report: hepatic artery pseudoaneurysm after liver transplantation: definitive treatment with a stent-graft after failed coil embolisation.

A 69-year-old woman presented with massive upper gastrointestinal bleeding owing to a ruptured hepatic pseudoaneurysm located at the surgical arterial anastomosis, 2 months after combined liver and kidney transplantation. Initially the pseudoaneurysm was successfully coiled but 3 weeks later recurrence of her symptoms occurred. Hepatic angiography revealed partial reperfusion of the coiled pseudoaneurysm; definitive treatment was performed by placement of an expanded-polytetrafluoroethylene (e-PTFE) covered coronary stent-graft, completely excluding the pseudoaneurysm. Radiological follow-up studies demonstrate a patent stent-graft functioning normally.

Aneurysm, False↗
PubMed2004

Gastro-intestinal stromal tumour of the duodenum: extreme presentation in two cases.

Gastro-intestinal stromal tumours (GIST) are primary mesenchymal tumours arising from the gastro-intestinal tract. They are uncommon visceral tumours, preferentially located in the stomach and small intestine. The present paper will discuss the clinical presentation of GIST in a 32-year-old female (Case 1) and in a 72-year-old female (Case 2). In both cases the tumour is located in the duodenum which appears to be a rather unusual location (4%) for GIST. This work will illustrate that duodenal GIST can occur in extreme presentations, diverging from vague complaints to directly life threatening symptoms.

Adult↗
PubMed2004

Transcatheter management of hepatic artery pseudoaneurysm following pancreaticoduodenectomy: a report of three cases.

Pseudoaneurysm formation is a rare, but potentially life threatening delayed complication of major pancreatic surgery. Redo surgery several weeks after pancreaticoduodenectomy can be hazardous, especially in debilitated patients. Percutaneous, transcatheter exclusion of the pseudoaneurysm by means of embolic coils can be an efficient, safe and minimally invasive alternative to open surgery with good mid- and long-term results. We present our experience in Three patients undergoing transcatheter embolization of hepatic artery pseudoaneurysms detected several weeks after Whipple's operation.

Aged↗
PubMed2004

Biocontrol agents of Botrytis cinerea tested in climate chambers by making artificial infection on tomato leafs.

To reduce the use of chemical agents, that are causing damage to the environment, in the fight against Botrytis cinerea, different BCA's were tested for their possibility to control Botrytis cinerea in a biological way. In order to investigate the effectiveness of the different micro organisms and Elot-Vis, experiments were carried out in climate chambers with 5 weeks old tomato plants. Leafs on the plant were inoculated with drops of a suspension that contained spores of Botrytis cinerea. The possible antagonists that were tested in these experiments were Trichoderma harzianum (Trichodex), T. asperellum (Biofungus), T. hamatum (T382), Bacillus subtilis (Serenade and Phytovit) and Pseudomonas aeruginosa (7NSK2 and KMPCH). For all these different micro organisms the direct and the indirect influence on Botrytis cinerea was investigated. In tests where the direct influence of the antagonists was examined, the spores of the moulds or the bacteria were suspended together with spores of Botrytis cinerea and subsequently drops of this suspension were pippeted on the leafs. After a while by ideal circumstances for Botrytis cinerea the infections on the inoculated leafs were counted. For the indirect influence of the antagonists, also leafs of 5 weeks old tomato plants were inoculated with a suspension of Botrytis cinerea spores. The roots of the tomato plants that were used for testing the indirect influence were treated during there growth with a suspension of the antagonist to see if induced systemic resistance pathway (ISR) was activated. For testing the effectiveness of Elot-Vis, tomato plants were sprayed a few times with a solution of this product during their growth. Results of the climate chamber test of the plants that were treated with Elot-Vis, showed a reduction of Botrytis cinerea infections on the inoculated leafs. Biological control agents seem to be not always very effective against Botrytis cinerea. The biological control agents that are containing micro organisms are also depending on the circumstances of the environment for an optimal development. These conditions are not always that optimal to compete with Botrytis cinerea or other micro organisms that are present on the plant.

Bacillus subtilis↗