In vivo quantification of fluorescent molecular markers in real-time: A review to evaluate the performance of five existing methods

With the advent of molecular-targeted fluorescent markers, there is a renewed interest in fluorescence quantification methods that are based on continuous wave excitation and multi-spectral image acquisition. However, little is known about their in vivo quantification performance. We reviewed the performance of five selected methods by analytically describing these and varying input parameters of irradiance, excitation geometry, collection efficiency, autofluorescence, melanin content, blood volume, blood oxygenation and tissue scattering using optical properties representing those for human skin. We identified one method that corrects for variations in all parameters. This requires image acquisition before and after marker administration, under identical geometry. Hence, it is suited for applications where the site of interest can be relocated (e.g. anaesthetized animals and dermatology). For applications where relocation is not possible, we identified a second method where the uncertainty in the fluorescence signal was ±20%. Hence, use of these methods can substantially aid in vivo fluorescence quantification compared to use of the raw fluorescence signal, as this changed by more than 3 orders of magnitude. Since these methods can be computed in real-time, they are of particular interest for applications where direct feedback is critical, as diagnostic screening or image-guided surgery.     

Dreaming during Anesthesia and Anesthetic Depth in Elective Surgery Patients: A Prospective Cohort Study

Background: Dreaming reported after anesthesia remains a poorly understood phenomenon. Dreaming may be related to light anesthesia and represent near-miss awareness. However, few studies have assessed the relation between dreaming and depth of anesthesia, and their results were inconclusive. Therefore, the authors tested the hypothesis that dreaming during anesthesia is associated with light anesthesia, as evidenced by higher Bispectral Index values during maintenance of anesthesia.

Methods: With approval, 300 consenting healthy patients, aged 18-50 yr, presenting for elective surgery requiring relaxant general anesthesia with a broad range of agents were studied. Patients were interviewed on emergence and 2-4 h postoperatively. The Bispectral Index was recorded from induction until the first interview. Dream content and form were also assessed.

Results: Dreaming was reported by 22% of patients on emergence. There was no difference between dreamers and nondreamers in median Bispectral Index values during maintenance (37 [23-55] vs. 38 [20-59]; P = 0.68) or the time at Bispectral Index values greater than 60 (0 [0-7] vs. 0 [0-31] min; P = 0.38). Dreamers tended to be younger and male, to have high home dream recall, to receive propofol maintenance or regional anesthesia, and to open their eyes sooner after surgery. Most dreams were similar to dreams of sleep and were pleasant, and the content was unrelated to surgery.     

Tacrolimus Exposure and Evolution of Renal Allograft Histology in the First Year After Transplantation

Tacrolimus has a narrow therapeutic window and is characterized by a large inter-individual variability in bioavailability. The impact of tacrolimus exposure on subclinical evolution of graft histology has not been studied in renal recipients. This analysis included 239 protocol biopsies (obtained at implantation, 3 and 12 months) of 120 consecutive kidney recipients treated with tacrolimus, mycophenolate mofetil (MMF) and corticosteroids. Biopsies were scored according to the Banff 2001 criteria and a chronicity score was calculated. Prospective pharmacokinetic data were included in the analysis (5544 tacrolimus predose blood concentrations and tacrolimus AUC(0-12) at 3 and 12 months). Higher donor age and higher number of human leukocyte antigen-DR (HLA-DR) mismatches were independent predictors of subclinical acute rejection at 3 months, present in 8.7% of patients. The number of HLA-DR mismatches was independently associated with biopsy-proven clinical acute rejection. Biopsy-proven acute rejection episodes and low mean tacrolimus exposure were independently associated with higher increase in chronicity scores between 3 and 12 months after transplantation. This observational study suggests that rejection phenomena and immune-mediated mechanisms remain important in the early progression of chronic allograft pathology. Tacrolimus doses or systemic exposure were not associated with lesions of calcineurin inhibitor nephrotoxicity, suggesting that other factors determine susceptibility to tacrolimus nephrotoxicity.     

Pancreas Graft Salvage Using Pancreatico-Duodenectomy With Enteric Drainage

As demand for donor pancreases increases, attempts are being made to utilize even marginal grafts for transplantation. Injury during pancreas recovery can predispose to posttransplant complications and graft loss. Early recognition and correction can salvage these grafts. The authors report an instance of poor segmental perfusion of the pancreas graft that was salvaged by pancreas head resection and enteric drainage through a Roux-en-Y pancreatico-jejunostomy.     

Long-term treatment with sildenafil in chronic thromboembolic pulmonary hypertension.

For chronic thromboembolic pulmonary hypertension not amenable to pulmonary endarterectomy, effective medical therapy is desired. In an open-label uncontrolled clinical trial, 104 patients (mean +/- sem age 62 +/- 11 yrs) with inoperable chronic thromboembolic pulmonary hypertension were treated with 50 mg sildenafil t.i.d. At baseline, patients had severe pulmonary hypertension (pulmonary vascular resistance 863 +/- 38 dyn.s.cm(-5)) and a 6-min walking distance of 310 +/- 11 m. Eight patients were in World Health Organization functional class II, 76 in class III and 20 in class IV. After 3 months' treatment, there was significant haemodynamic improvement, with reduction of pulmonary vascular resistance to 759 +/- 62 dyn.s.cm(-5). The 6-min walking distance increased significantly to 361 +/- 15 m after 3 months' treatment, and to 366 +/- 18 m after 12 months' treatment. A subset of 67 patients received a single dose of 50 mg sildenafil during initial right heart catheterisation. The acute haemodynamic effect of this was not predictive of long-term outcome. In this large series of patients with inoperable chronic thromboembolic pulmonary hypertension, open-label treatment with sildenafil led to significant long-term functional improvement. The acute effect of sildenafil may not predict the long-term outcome of therapy.