Assessment of angiotensin II receptor blockade in humans using a standardized angiotensin II receptor-binding assay.

An in vitro angiotensin II (AngII) receptor-binding assay was developed to monitor the degree of receptor blockade in standardized conditions. This in vitro method was validated by comparing its results with those obtained in vivo with the injection of exogenous AngII and the measurement of the AngII-induced changes in systolic blood pressure. For this purpose, 12 normotensive subjects were enrolled in a double-blind, four-way cross-over study comparing the AngII receptor blockade induced by a single oral dose of losartan (50 mg), valsartan (80 mg), irbesartan (150 mg), and placebo. A significant linear relationship between the two methods was found (r = 0.723, n = 191, P<.001). However, there exists a wide scatter of the in vivo data in the absence of active AngII receptor blockade. Thus, the relationship between the two methods is markedly improved (r = 0.87, n = 47, P<.001) when only measurements done 4 h after administration of the drugs are considered (maximal antagonist activity observed in vivo) suggesting that the two methods are equally effective in assessing the degree of AT-1 receptor blockade, but with a greatly reduced variability in the in vitro assay. In addition, the pharmacokinetic/pharmacodynamic analysis performed with the three antagonists suggest that the AT-1 receptor-binding assay works as a bioassay that integrates the antagonistic property of all active drug components of the plasma. This standardized in vitro-binding assay represents a simple, reproducible, and precise tool to characterize the pharmacodynamic profile of AngII receptor antagonists in humans.

Varicella Zoster Virus CNS disease in hematopoietic cell transplantation: A single center experience

Background: Varciella Zoster Virus (VZV) can lead to serious complications in Hematopoietic Cell Transplant (HCT) recipients. Central nervous system (CNS) VZV can be one of the most devastating infections in transplant recipients, yet little is known about this rare disease. Objectives: To describe CNS VZV in the post-transplant period and to define potential risk factors in the HCT population. Methods: We reviewed the course of all patients who received a first HCT at the Fred Hutchinson Cancer Center (FHCRC) in Seattle, WA from 1/1996 through 12/2007. Data were collected retrospectively using the Long-Term Follow-Up database, which includes on-site examinations, outside records, laboratory tests, and yearly questionnaires. Patients were classified as CNS VZV if they had laboratory confirmation of VZV in the cerebrospinal fluid (CSF), or had zoster with associated clinical and laboratory findings consistent with CNS disease. Results: A total of six patients developed VZV CNS disease during the evaluation period (table 1). Diagnosis was confirmed in 3/6 by detection of VZV in CSF by PCR. All other patients had a clinical diagnosis based on the presence of CNS symptoms, zoster, lymphocytic pleiocytosis, and response to IV acyclovir. Patients who developed CNS disease had a mean age of 42 years (range 34-51) at time of transplant. CNS disease developed at a mean of 9 months posttransplantation (range 0.5-24 months), and severity varied, ranging from meningitis (3/6) to encephalitis/myelitis (3/6). All had active graft-versus host disease (GHVD) and all were being treated with immunosuppressive therapy at time of diagnosis. Fever and headache were the most common symptoms, but patients who developed focal CNS findings or seizures (3/6) had a more complicated clinical course. While most patients presented with classic VZV/zoster skin lesions, 2/6 patients had no dermatologic findings associated with their presentation. Four (66%) of patients who developed VZV CNS disease died, two related to VZV complications despite aggressive antiviral therapy. Conclusions: In this cohort of HCT patients, VZV CNS disease was a rare complication. Mortality due to CNS VZV is high, particularly in patients who develop focal neurologic findings or seizures. Even in the absence of skin lesions, VZV CNS disease should be considered in patients who develop fevers and neurologic symptoms.

Meningococcal disease in a kidney transplant recipient with mannose-binding lectin (MBL) deficiency

Background: There is an increasing amount of data associating MBL deficiency with a higher susceptibility to meningococca[ disease. In addition, meningococca[ disease has been reported in patients with various immunosuppressive conditions. However, to our knowledge, only three cases of meningococca[ disease have been reported in solid organ recipients (SOT). Methods & Results: A 32 year-old male patient underwent cadaveric kidney transplantation for endstage renal disease of unknown origin. On day 71 post-transplantation he developed fever (39.6°C), shaking chilis, and tachycardia without hypotension. At this time, immunosuppression consisted of tacro[imus, prednisone 10mg daily and mycopheno[ ate mofeti[ 2 g daily. Physical examination on admission was normal, except for two small petechia[ lesions on the forearm. No meningeal signs were present. Three sets of blood cultures grew Neisseria meningitidis group C susceptible to ceftriaxone (MIC=0.003mg/[). Antibiotic therapy consisted in intravenous ceftriaxone 2 g per day for a total duration of 7 days. Serum immunog[obu[in levels, C3, C4 and CHS0 were normal However, using a method to screen for the functional activity of a[[ three pathways of complement (Wies[ab, Lund, Sweden), no activation via the MBL pathway could be detected (0%). A subsequent quantification of MBL pathway components revealed normal levels of MASP 2 but undetectab[e amounts of MBL (below 10 ng/m[, normal range: >500 ng/m[). Conclusion: Since the exact incidence and the possible relationship between meningococca[ disease and organ transplantation is not we[[ understood, we strongly encourage transplantation centers to report additional cases. The potential clinical usefu[ ness of screening SOT candidates for MBL deficiency in relation to infectious complications after transplantation remains to be determined.

Vaccinia immune globulin: current policies, preparedness, and product safety and efficacy.

In 1980 the World Health Organization declared that smallpox was eradicated from the world, and routine smallpox vaccination was discontinued. Nevertheless, samples of the smallpox virus (variola virus) were retained for research purposes, not least because of fears that terrorist groups or rogue states might also have kept samples in order to develop a bioweapon. Variola virus represents an effective bioweapon because it is associated with high morbidity and mortality and is highly contagious. Since September 11, 2001, countries around the world have begun to develop policies and preparedness programs to deal with a bioterror attack, including stockpiling of smallpox vaccine. Smallpox vaccine itself may be associated with a number of serious adverse events, which can often be managed with vaccinia immune globulin (VIG). VIG may also be needed as prophylaxis in patients for whom pre-exposure smallpox vaccine is contraindicated (such as those with eczema or pregnant women), although it is currently not licensed in these cases. Two intravenous formulations of VIG (VIGIV Cangene and VIGIV Dynport) have been licensed by the FDA for the management of patients with progressive vaccinia, eczema vaccinatum, severe generalized vaccinia, and extensive body surface involvement or periocular implantation following inadvertent inoculation.

Reversible and irreversible pollutant-induced bacterial cellular stress effects measured by ethidium bromide uptake and efflux.

Chemical pollution is known to affect microbial community composition but it is poorly understood how toxic compounds influence physiology of single cells that may lay at the basis of loss of reproductive fitness. Here we analyze physiological disturbances of a variety of chemical pollutants at single cell level using the bacterium Pseudomonas fluorescens in an oligotrophic growth assay. As a proxy for physiological disturbance we measured changes in geometric mean ethidium bromide (EB) fluorescence intensities in subpopulations of live and dividing cells exposed or not exposed to different dosages of tetradecane, 4-chlorophenol, 2-chlorobiphenyl, naphthalene, benzene, mercury chloride, or water-dissolved oil fractions. Because ethidium bromide efflux is an energy-dependent process any disturbance in cellular energy generation is visible as an increased cytoplasmic fluorescence. Interestingly, all pollutants even at the lowest dosage of 1 nmol/mL culture produced significantly increased ethidium bromide fluorescence compared to nonexposed controls. Ethidium bromide fluorescence intensities increased upon pollutant exposure dosage up to a saturation level, and were weakly (r(2) = 0.3905) inversely correlated to the proportion of live cells at that time point in culture. Temporal increase in EB fluorescence of growing cells is indicative for toxic but reversible effects. Cells displaying high continued EB fluorescence levels experience constant and permanent damage, and no longer contribute to population growth. The procedure developed here using bacterial ethidium bromide efflux pump activity may be a useful complement to screen sublethal toxicity effects of chemicals.

Prospective study on procalcitonin and other systemic infection markers in patients with leukocytosis.

OBJECTIVE: To better assess the diagnosis of an infection in patients presenting at an emergency department with peripheral blood leukocytosis (>10 x 10(9) cells/l) on laboratory testing. METHODS: We prospectively evaluated serum procalcitonin concentration (PCT), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Patients were divided into two groups according to their final diagnosis: patients with infection and those without infection. PCT, CRP, and ESR were compared between these groups. Sensitivity, specificity, positive predictive values, negative predictive values, receiver operating characteristic curves, and areas under the curves were calculated for each biological measurement. RESULTS: Out of 173 patients, 99 (57%) had a final diagnosis of systemic infection. If a cutoff point of 0.5 ng/ml is considered, procalcitonin concentration had a sensitivity of 0.57, a specificity of 0.85, a negative predictive value of 0.59, and a positive predictive value of 0.84 for the diagnosis of a systemic infection. Adding CRP or ESR to PCT gave no more information (p=0.84). CONCLUSIONS: Only about half of the patients attending the emergency department with leukocytosis were suffering from an infection. Determination of the procalcitonin level may be useful for these patients, particularly in the case of a value higher than 0.5 ng/ml.

Absence of BK viremia clearance after low-dose cidofovir therapy in kidney transplant recipients with BK virus associated nephropathy

Background: BK virus associated nephropathy occurs in 1-10% of kidney transplant recipients and may be a cause of graft loss. This infection is difficult to manage because of the absence of specific therapy. Cidofovir, a DNA polymerase inhibitor approved for the treatment of CMV retinitis, has shown in vitro activity against BK virus and some clinical efficacy when used at low-dose in uncontrolled series. Objective: To assess the efficacy of low-dose Cidofovir in the treatment of BK virus associated nephropathy. Method: Two adult kidney transplant recipients with biopsy-proven BK nephropathy and persistent high viremia (>10,000 copies/ml) despite 3-month reduction of immunosuppressive therapy were treated by Cidofovir 0.5 mg/kg fortnightly for a total of 16 weeks (8 doses). Clinical response was assessed by following BK viremia. Results: No decrease in BK viremia was observed at any point during cidofovir therapy (see figure). Creatinine clearance remained stable during therapy and no side-effects of Cidofovir were observed. Conclusions: Low-dose Cidofovir therapy was not associated with a clearance or with a significant decrease of BK viremia. This pilot study does not confirm previous reports suggesting clinical efficacy of Cidofovir for BK virus associated nephropathy.

RIP4 (DIK/PKK), a novel member of the RIP kinase family, activates NF-kappa B and is processed during apoptosis.

RIP1 and its homologs, RIP2 and RIP3, form part of a family of Ser/Thr kinases that regulate signal transduction processes leading to NF-kappa B activation. Here, we identify RIP4 (DIK/PKK) as a novel member of the RIP kinase family. RIP4 contains an N-terminal RIP-like kinase domain and a C-terminal region characterized by the presence of 11 ankyrin repeats. Overexpression of RIP4 leads to activation of NF-kappa B and JNK. Kinase inactive RIP4 or a truncated version containing the ankyrin repeats have a dominant negative (DN) effect on NF-kappa B induction by multiple stimuli. RIP4 binds to several members of the TRAF protein family, and DN versions of TRAF1, TRAF3 and TRAF6 inhibit RIP4-induced NF-kappa B activation. Moreover, RIP4 is cleaved after Asp340 and Asp378 during Fas-induced apoptosis. These data suggest that RIP4 is involved in NF-kappa B and JNK signaling and that caspase-dependent processing of RIP4 may negatively regulate NF-kappa B-dependent pro-survival or pro-inflammatory signals.

Pharmacokinetic and pharmacodynamic evaluation of valganciclovir in solid organ transplant patients

Goal: To validate oral vatgancictovir (VGC) in the prophylaxis of CMV infection in Lung (Lu) and Liver (L) recipients and in the treatment of CMV infection/disease in solid organ transplant recipients, using pharmacokinetic and pharmacodynamic studies in comparison with i/v gancicLovir (GCV). Methods: patients undergoing organ transpLantation donor or recipient CMV-seropositive receiving VGC prophylaxis for a period of 3 months (D+/R- Lung recipients, 6 months) were enroLLed. Heart (H), Lu, and L recipients received 900mg VGC q.d., adjusted to kidney (K) function. No K recipients received more than 450mg of VGC q.d. GCV trough (Ctrough) and peak (Cpeak = 3 hours after drug administration) LeveLs, and CMV DNA were measured at 7, 30, and 60 days post-transpLant (prophyLactic study). Patients who developed CMV infection/disease after stopping prophylaxis were treated with VGC (1800mg per day adjusted to K function and GCV blood LeveLs). GCV trough and peak LeveLs, and CMV DNA were measured weekly for the first 3 weeks and biweekly thereafter, until therapy cessation (therapeutic study). PLasma concentration of GCV is measured by HPLC. Results: In the first 8 prophyLaxed patients (6 K, and 1 L and 1 H transplant recipient) of 450mg VGC q.d., the average GCV concentration was 0.5±0.3 mg/t at trough, and 3.9±l.0mg/t 3 hours after administration. Inter-patient variability was substantiaL, especiaLLy for Ctrough (63% of total variance), which correlated with the patient's estimated gtomerutar filtration rate (r square = 42%). No CMV DNA was detected during VGC prophy- Laxis. Two patients (1 H and 1 L) were treated for Late CMV disease. Average GCV Cpeak were 8.9±2.3 mg/L and 4.6±0.5 rag/L, and GCV Ctrough were 2.0±0.9 mg/t and 1.6±0.2 mg/t respectively in each patient during induction phase. VGC treatment afforded a decrease in CMV DNA from 5.2 and 4.4 Log copies/10E6 cettutes at week 0, to 3.9 and 3.0 at week 1, and 3.3 and 2.1 at week 3, respectively.

No detectable indirect effects of late-onset Cytomegalovirus disease after valganciclovir (VGC) prophylaxis in kidney transplant recipients

Background: Cytomegalovirus (CMV) disease remains an important cause of morbidity after kidney transplantation and has been associated with acute rejection, graft loss and other indirect effects. A 3-month course of VGC prophylaxis reduces the incidence of CMV disease. However, little is known about the indirect effects of lateonset CMV disease after VGC prophylaxis. Objective: To evaluate the impact and indirect consequences of late-onset CMV disease after VGC prophylaxis in kidney transplant recipients. Methods: Retrospective analysis of 61 consecutive adult kidney transplant recipient with positive CMV serology (donor or recipient) who received VGC prophylaxis for 3 months and completed a follow-up of at least 2 years post-transplantation. Patients who developed CMV disease within 1 year after transplantation were compared to CMV disease-free patients for renal function (plasma creatinine values) at 1, 6, 12 and 24 months and for the incidence of graft loss, acute rejection, diabetes, cancer and opportunistic infections. Results: 8/61 (13%) patients developed CMV disease at a median of 131 days after transplantation (range: 98-220). The CMV incidence in D+/R- high risk patients was 6/18 (33%), while it was 2/43 (5%) in intermediate-risk patients (p < 0.01). All 8 patients were treated by oral valganciclovir (median 39 days; range: 19-119) with a complete resolution of CMV disease. As shown in the figure, there was no difference in creatinine values between the two groups at any time during follow-up. There was no graft loss, and the incidence of acute rejection, cancer and opportunistic infections did not differ between the two groups. The incidence of post-transplant diabetes was higher (38% vs 15%) in patients with CMV disease, but this difference was not significant (p = 0.4). Conclusions: An incidence of 13% of late-onset CMV disease was observed despite 3 months VGC prophylaxis. However, no indirect consequences were found. Moreover, therapy of CMV disease by oral VGC was effective and safe. Larger trials are needed to study whether late-onset CMV disease is associated with indirect consequences, as described with early-onset CMV.