Graft involvement by Legionella in a liver transplant recipient.

Legionella pneumophila, serogroup 1, was identified by direct immunofluorescence in the lung and liver graft from a 2 1/2-month-old infant who underwent orthotopic liver transplantation because of fulminant hepatic failure secondary to neonatal hepatitis. The patient died of respiratory failure owing to this infection 22 days after transplantation despite treatment with erythromycin lactobionate. To our knowledge, this represents the first reported case of hepatic infection with Legionella in liver transplant recipients.     

Theoretical study of catalytic mechanism for single-site water oxidation process

Water oxidation is a linchpin in solar fuels formation, and catalysis by single-site ruthenium complexes has generated significant interest in this area. Combining several theoretical tools, we have studied the entire catalytic cycle of water oxidation for a single-site catalyst starting with [Ru^II(tpy)(bpm)(OH₂)]²⁺ (i.e., [Ru^II-OH₂]²⁺; tpy is 2,2^′∶6^′,2^′′-terpyridine and bpm is 2,2′-bypyrimidine) as a representative example of a new class of single-site catalysts. The redox potentials and pK_a calculations for the first two proton-coupled electron transfers (PCETs) from [Ru^II-OH₂]²⁺ to [Ru^IV = O]²⁺ and the following electron-transfer process to [Ru^V = O]³⁺ suggest that these processes can proceed readily in acidic or weakly basic conditions. The subsequent water splitting process involves two water molecules, [Ru^V = O]³⁺ to generate [Ru^III-OOH]²⁺, and H₃O⁺ with a low activation barrier (∼10 kcal/mol). After the key O---O bond forming step in the single-site Ru catalysis, another PECT process oxidizes [Ru^III-OOH]²⁺ to [Ru^IV-OO]²⁺ when the pH is lower than 3.7. Two possible forms of [Ru^IV-OO]²⁺, open and closed, can exist and interconvert with a low activation barrier (< 7 kcal/mol) due to strong spin-orbital coupling effects. In Pathway 1 at pH = 1.0, oxygen release is rate-limiting with an activation barrier ∼12 kcal/mol while the electron-transfer step from [Ru^IV-OO]²⁺ to [Ru^V - OO]³⁺ becomes rate-determining at pH = 0 (Pathway 2) with Ce(IV) as oxidant. The results of these theoretical studies with atomistic details have revealed subtle details of reaction mechanisms at several stages during the catalytic cycle. This understanding is helpful in the design of new catalysts for water oxidation.     

Splitting CO2 into CO and O2 by a single catalyst

The metal complex [(tpy)(Mebim-py)Ru^II(S)]²⁺ (tpy = 2,2^′ : 6^′,2^′′-terpyridine; Mebim-py = 3-methyl-1-pyridylbenzimidazol-2-ylidene; S = solvent) is a robust, reactive electrocatalyst toward both water oxidation to oxygen and carbon dioxide reduction to carbon monoxide. Here we describe its use as a single electrocatalyst for CO₂ splitting, CO₂ → CO + 1/2 O₂, in a two-compartment electrochemical cell.     

Evaluation of Previously Assigned Antibody Concentrations in Pneumococcal Polysaccharide Reference Serum 89SF by the Method of Cross-Standardization

An enzyme-linked immunosorbent assay (ELISA) and the antibody concentrations assigned to different pneumococcal capsular polysaccharide types were used to estimate concentrations of antibody to additional pneumococcal types in reference serum 89SF and to confirm assigned antibody values. This was possible because the slopes of curves of antibody binding to all polysaccharide types evaluated (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F) were similar. The point estimates for total anti-pneumococcal antibody and immunoglobulin G (IgG) antibody determined by cross-standardization by an ELISA based on use of methylated human serum albumin (mHSA) to improve the efficiency of polysaccharide binding to the ELISA plate differed by less than 40% from those reported by Quataert et al. (Clin. Diagn. Lab. Immunol. 2:590–597, 1995) for types 1, 4, 6B, 7F, 9V, 14, 18C, and 23F. However, large differences were found between the assigned values and those obtained by our mHSA ELISA for types 3 and 19F. The mHSA ELISA and the direct polysaccharide coat ELISA may not measure antibodies to the same epitopes on polysaccharides of types 3 and 19F. The functional importance of these different antibody specificities is being investigated. We have thus confirmed the assigned IgG antibody values for most types by a different method and have extended antibody assignments to several additional types.     

Anesthesia (19)

Respiratory gas exchange and hemodynamics during lumbar epidural anesthesia: effects of lidocaine with and without epinephrine. (New England Medical Center, Tufts University School of Medicine, Boston, MA) Reg Anesth Pain Med 2000;25:380–384.
In this study, 12 healthy patients (age, 22 to 46 years) undergoing surgery on the knee were randomly assigned to receive either 2% lidocaine (Group L) or 2% lidocaine with epinephrine 5 μg · mL⁻¹ (Group E), approximately 20 mL, over 10 min via lumbar epidural catheter. Total-body oxygen consumption (VO₂) and carbon dioxide production (VCO₂) were determined by indirect calorimetry; hemodynamic measurements were obtained by noninvasive thoracic electrical bioimpedance. Values of VO₂, VCO₂, heart rate (HR), cardiac index (CI), and mean arterial blood pressure (MAP) were determined every minute and averaged every 5 min for 30 min. Comparisons were made with analysis of variance (ANOVA) (within groups) and t -tests (between groups). Differences were considered significantly different if P < 0.05. VO₂ did not change in either group, while VCO₂ increased significantly by 22% at 20 min in Group E. Increases in HR were apparent in both groups, with significantly greater increases in Group E. CI did not change in Group L, but increased by 41% in Group E. MAP decreased significantly by 11% in Group E, but did not change in Group L. Conclude that the addition of epinephrine, 5 μg · mL⁻¹, to the epidural injection of 2% lidocaine is associated with changes not only in hemodynamics, but also in respiratory gas exchange.     

GC-MS analysis of the lipophilic principles of Echinacea purpurea and evaluation of cucumber mosaic cucumovirus infection

An analytical GC–MS method based on nonpolar fused silica capillary column was developed to analyze the lipophilic constituents, mainly alkamides, from the root extracts of Echinacea purpurea (L.) Moench. In particular, the proposed method was applied to evaluate the phytochemical impacts of cucumber mosaic cucumovirus (CMV) infection on the plant's lipophilic marker phytochemicals. Methanolic (70% v/v) extracts, obtained from root materials by ultrasonic treatments, were subjected to liquid–liquid extraction with n-hexane-ethyl acetate (1:1 v/v) to recover the lipophilic, volatile to semivolatile, principles. Seventeen components, including the 11 alkamides known to E. purpurea roots, were identified in the GC–MS traces of the analyzed fractions and efficiently separated in a turnaround time of 25 min. CMV infection was found to be responsible for significant variations in the relative compositions of the major constituents, in particular germacrene D, Dodeca-2E, 4E, 8Z, 10Z(E)-tetraenoic acid isobutylamide cis/trans isomers, Undeca-2Z, 4E-diene-8, 10-diynoic acid isobutylamide and Dodeca-2E, 4Z-diene-8, 10-diynoic acid isobutylamide.     

Nephrogenic fibrosing dermopathy after liver transplantation successfully treated with plasmapheresis

Nephrogenic fibrosing dermopathy (NFD) is a recently described cutaneous fibrosing disorder associated with renal dysfunction. It appears similar to scleromyxedema but with some notable exceptions, including the lack of involvement of the face and absence of plasma cells on histology, systemic involvement, and paraproteinemia. Patients can present with thickened or edematous skin with indurated papules and plaques involving the extremities and the trunk. We report the first three cases of NFD after liver transplantation successfully treated with plasmapheresis. Two patients underwent liver transplantation for hepatitis C virus-induced cirrhosis and one for hepatitis B virus-induced cirrhosis. All the patients had encephalopathy, refractory ascites, and malnutrition prior to transplantation. Like those patients with NFD, all three of our patients had renal dysfunction and required hemodialysis before and after transplantation. Two were not dependent on dialysis at the time of diagnosis, however. These patients had excellent liver allograft function, but the other patient had allograft failure secondary to recurrent hepatitis C. Immunosuppression therapy consisted of basiliximab, mycophenolate mofetil, calcineurin inhibitor, and prednisone. The patients developed "woody" skin induration of the distal extremities, erythematous papules, and contractures at 1, 2, and 120 months after transplantation. Skin biopsies resembled NFD. No paraproteinemia was evident. One to three 5-day courses of plasmapheresis resulted in moderate to marked clinical improvement. The improvement of the kidney function in two of our patients did not appear to correlate with that of the skin disorder, because the kidney function was improving at the time the diagnosis of NFD was made. In conclusion, we report the first three cases of NFD after liver transplantation. Plasmapheresis was moderately successful in resolving the skin-indurated papules, severe skin induration, and associated joint contractures. Preliminary studies (unpublished data) show that decreasing plasma levels of transforming growth factor-beta1 after plasmapheresis appear to correlate with the amelioration of this clinical condition.