Dual-task processing in younger and older adults: similarities and differences revealed by fMRI.
ABSTRACT fMRI was used to explore age differences in the neural substrate of dual-task processing. Brain activations when there was a 100 ms SOA between tasks, and task overlap was high, were contrasted with activations when there was a 1000 ms SOA, and first task processing was largely complete before the second task began. Younger adults (M=21 yrs) showed activation in dorsolateral prefrontal cortex and in parietal areas as well as in ventral medial frontal cortex and sub-lobar areas. Activations in older adults (M=71 yrs) did not differ significantly from younger adults except for higher activations in occipital and polar prefrontal cortex. The results were well fit by a model with two networks managing dual-task interference, a medial prefrontal network that detects changes in the stimulus situation and maps them to associated changes in the valence of response mappings and a lateral frontal-parietal network that initiates and carries out the shift from one task to the other. The additional activations in older adults as a group and the correlations of individual differences in activation with performance were consistent with recruitment within each of these networks. Alternative explanations such as hemispheric asymmetry reduction and reactive rather than proactive processing in older adults were not supported.
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ABSTRACT: Simultaneous pancreas-kidney transplantation (SPK) has evolved as an effective treatment for patients with end-stage nephropathy due to type 1 diabetes mellitus. This report analyses the spectrum of surgical complications among patients receiving tacrolimus and cyclosporin microemulsion (ME)-based therapy for SPK transplantation. The analysis included 205 patients randomly assigned to tacrolimus (n = 103) or cyclosporin-ME (n = 102) in the Euro-SPK 001 study. Surgical complications were defined as any intervention in the 3-month post-operative course related to the transplant procedure. In the tacrolimus vs cyclosporin-ME group, repeat laparotomy was required by fewer patients (26 vs 43%, respectively; P = 0.01) and at a later stage post-transplant (26+/-26 vs 14+/-17 days; P = 0.05). Also, thrombosis of graft vessels (2 vs 9%; P = 0.03) and repeat laparotomy for intra-abdominal haemorrhage within the first 3 months (8 vs 22%; P = 0.005) occurred significantly less frequently with tacrolimus vs cyclosporin-ME. A donor age of > or =45 years was a significant determinant for surgical complications requiring repeat laparotomy, regardless of the type of immunosuppression. Portal anastomosis was the safest method of endocrine venous drainage, and Roux-en-Y loop for enteric exocrine drainage was associated with a higher re-operation rate than duodenoenterostomy. Repeat laparotomy had no impact on patient survival, but significantly reduced kidney and pancreas graft survival in the cyclosporin-ME group (kidney: P<0.01; pancreas: P<0.001) and in both groups combined (P < or = 0.05 and P<0.001, respectively). The immunological benefits of tacrolimus compared with cyclosporin-ME treatment result in a lower incidence of repeat laparotomies post-transplant and a reduced in-hospital stay. Fewer repeat laparotomies translate into improved pancreas and kidney graft survival.Nephrology Dialysis Transplantation 05/2005; 20 Suppl 2:ii54-62. · 3.37 Impact Factor
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ABSTRACT: Reperfusion pancreatitis and graft thrombosis often induce early graft loss in simultaneous pancreas-kidney (SPK) transplantation. Antithrombin (AT) is a coagulatory inhibitor with pleiotropic activities that reduces experimental ischemia/reperfusion injury. This study retrospectively analyses prophylactic high-dose AT application in patients with first SPK. In an university transplantation center, 53 consecutive patients with SPK were studied without randomization. In one group, 3000 IU of AT was given intravenously before pancreatic reperfusion (AT, n = 24). Patients receiving standard therapy including postoperative AT supplementation (controls, n = 29) served as controls. Daily blood sampling was performed as a part of the clinical routine during four postoperative days. There were no differences in demographic and laboratory parameters [donor/recipient age, ischemia time, perfusion solution, body weight, mismatches] between both groups. Baseline creatinine values were lower in the control group versus AT group (P < 0.05). Coagulatory parameters and bleeding incidence were not influenced by AT, while incidence of graft thrombosis was reduced (control: 7/29; AT: 4/24; relative reduction of risk: -33%; P < 0.05). Single-shot AT application during SPK modulated serum lipase activity on postoperative days 2 and 3, and minimized risk for graft thromboses without increasing perioperative bleeding. This new concept should deserve testing in a prospective clinical trial.Transplant International 06/2006; 19(6):458-65. · 3.16 Impact Factor
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ABSTRACT: Postoperative pancreatic fistula (POPF) is still regarded as a major complication. The incidence of POPF varies greatly in different reports, depending on the definition applied at each surgical center. Our aim was to agree upon an objective and internationally accepted definition to allow comparison of different surgical experiences. An international panel of pancreatic surgeons, working in well-known, high-volume centers, reviewed the literature on the topic and worked together to develop a simple, objective, reliable, and easy-to-apply definition of POPF, graded primarily on clinical impact. A POPF represents a failure of healing/sealing of a pancreatic-enteric anastomosis or a parenchymal leak not directly related to an anastomosis. An all-inclusive definition is a drain output of any measurable volume of fluid on or after postoperative day 3 with an amylase content greater than 3 times the serum amylase activity. Three different grades of POPF (grades A, B, C) are defined according to the clinical impact on the patient's hospital course. The present definition and clinical grading of POPF should allow realistic comparisons of surgical experiences in the future when new techniques, new operations, or new pharmacologic agents that may impact surgical treatment of pancreatic disorders are addressed.Surgery 08/2005; 138(1):8-13. · 3.37 Impact Factor