Clinical pharmacokinetics of norfloxacin-glycine acetate after intravenous and oral administration in pigs

The pharmacokinetics and dosage regimen of norfloxacin-glycine acetate (NFLXGA) was investigated in pigs after a single intravenous (i.v.) or oral (p.o.) administration at a dosage of 7.2 mg/kg body weight. After both i.v. and p.o. administration, plasma drug concentrations were best fitted to an open two-compartment model with a rapid distribution phase. After i.v. administration of NFLXGA, the distribution (t1/2α) and elimination half-life (t1/2β) were 0.36 ± 0.07 h and 7.42 ± 3.55 h, respectively. The volume of distribution of NFLXGA at steady state (Vdss) was 4.66 ± 1.39 l/kg. After p.o. administration of NFLXGA, the maximal absorption concentration (Cmax) was 0.43 ± 0.06 µg/ml at 1.36 ± 0.39 h (Tmax). The mean absorption (t1/2ka) and elimination half-life (t1/2β) of NFLXGA were 0.78 ± 0.27 h and 7.13 ± 1.41 h, respectively. The mean systemic bioavailability (F) after p.o. administration was 31.10 ± 15.16%. We suggest that the optimal dosage calculated from the pharmacokinetic parameters is 5.01 mg/kg per day i.v. or 16.12 mg/kg per day p.o

Cytomegalovirus Ventriculoencephalitis after Unrelated Double Cord Blood Stem Cell Transplantation with an Alemtuzumab-containing Preparative Regimen for Philadelphia-positive Acute Lymphoblastic Leukemia

Despite the prophylaxis and preemptive strategies using potent antiviral agents, cytomegalovirus (CMV) remains a major infectious cause of morbidity and mortality in allogeneic stem cell transplantation (SCT) recipients. Delayed immune reconstitution after SCT, such as cord blood and T-cell depleted SCT with the use of alemtuzumab, has been associated with an increased frequency of CMV disease as well as CMV reactivation. CMV disease involving central nervous system is an unusual presentation in the setting of SCT. We report a case of CMV ventriculoencephalitis after unrelated double cord blood SCT with an alemtuzumab-containing preparative regimen for Philadelphia-positive acute lymphoblastic leukemia

Current Trends of Infectious Complications following Hematopoietic Stem Cell Transplantation in a Single Center

This study was to analyze the infectious complications after hematopoietic stem cell transplantation (HSCT) according to the recent changes of HSCT. Medical records of 379 adult patients who underwent HSCT consecutively at Catholic HSCT Center from January 2001 to December 2002 were reviewed retrospectively. Allogeneic HSCT accounted for 75.7% (287/379) and autologous HSCT for 24.3% (92/379). During pre-engraftment period, bacterial infection was predominant, and E. coli was still the most common organism. After engraftment, viral infection was predominant. The incidence of invasive fungal infection showed bimodal distribution with peak correlated with neutropenia and graft-versus-host disease (GVHD). The overall mortality and infection-related mortality rates according to 3 periods were as follows; during pre-engraftment, 3.16% (12/379) and 1.8% (7/379); during midrecovery period, 7.9% (29/367) and 4.1% (15/367); during late-recovery period, 26.9% (91/338), and 15.9% (54/338). Risk factors for infection-related mortality were as follows; during pre-engraftment period, fungal infection and septic shock; during the mid-recovery period, hemorrhagic cystitis and delayed engraftment; during the late-recovery period, fungal infection, chronic GVHD, and relapse. In conclusion, infection was still one of the main complications after HSCT and highly contributes to mortality. The early diagnosis and the effective vaccination strategy are needed for control of infections

Development of Safe and Non-Self-Immunogenic Mucosal Adjuvant by Recombinant Fusion of Cholera Toxin A1 Subunit with Protein Transduction Domain

Potential use of cholera toxin (CT) as a mucosal vaccine adjuvant has been documented in a variety of animal models. However, native CT is highly toxic to be used as a mucosal adjuvant in humans. Here, we demonstrate a new approach to generate a mucosal adjuvant by replacing the B subunit of CT with HIV-1 Tat protein transduction domain (PTD), which efficiently delivers fusion proteins into the cell cytoplasm by unspecific binding to cell surface. We compared the adjuvanticity and toxicity of Tat PTD-CTA1-Tat PTD (TCTA1T) with those of CT. Our results indicate that intranasal (i.n.) delivery of ovalbumin (OVA) with TCTA1T significantly augments the OVA-specific systemic and mucosal antibody responses to levels comparable to those seen with CT adjuvant. Moreover, in vivo cytotoxic T lymphocyte activity elicited by TCTA1T was significantly higher than that elicited by a mutant TCTA1T (TmCTA1T) lacking ADP-ribosyltransferase function. In addition, coadministration of influenza M2 protein with TCTA1T conferred near complete protection against lethal influenza virus challenge. Importantly, TCTA1T, in contrast to CT, did not induce serum IgG antibody responses to itself and was shown to be nontoxic. These results suggest that TCTA1T may be a safe and effective adjuvant when given by mucosal routes

Comparison of Quantitative Cytomegalovirus Real-time PCR in Whole Blood and pp65 Antigenemia Assay: Clinical Utility of CMV Real-time PCR in Hematopoietic Stem Cell Transplant Recipients

Successful preemptive therapy for cytomegalovirus (CMV) infection in transplant patients depends on the availability of sensitive, specific, and timely diagnostic tests for CMV infection. Although the pp65 antigenemia assay has been widely used for this purpose, real-time quantification of CMV DNA has recently been recognized as an alternative diagnostic approach. However, the guidelines for antiviral therapy based on real-time quantitative polymerase chain reaction (RQ-PCR) have yet to be established. From November 2004 to March 2005, a total of 555 whole blood samples from 131 hematopoietic stem cell transplant (HSCT) recipients were prospectively collected. RQ-PCR was conducted using an Artus® CMV LC PCR kit (QIAGEN). Both qualitative and quantitative correlations were drawn between the two methods. Exposure to the antiviral agent influenced the results of the two assays. Additionally, the discrepancy was observed at low levels of antigenemia and CMV DNA load. Via ROC curve analysis, the tentative cutoff value for preemptive therapy was determined to be approximately 2×104 copies/mL (sensitivity, 80.0%; specificity, 50.0%) in the high risk patients, and approximately 3×104 copies/mL (sensitivity, 90.0%; specificity, 70.0%) in the patients at low risk for CMV disease. Further study to validate the optimal cutoff value for the initiation of preemptive therapy is currently underway

An ELF4 Hypomorphic Variant Results in NK Cell Deficiency

NK cell deficiencies (NKD) are a type of primary immune deficiency in which the major immunologic abnormality affects NK cell number, maturity, or function. Since NK cells contribute to immune defense against virally infected cells, patients with NKD experience higher susceptibility to chronic, recurrent, and fatal viral infections. An individual with recurrent viral infections and mild hypogammaglobulinemia was identified to have an X-linked damaging variant in the transcription factor gene ELF4. The variant does not decrease expression but disrupts ELF4 protein interactions and DNA binding, reducing transcriptional activation of target genes and selectively impairing ELF4 function. Corroborating previous murine models of ELF4 deficiency (Elf4-/-) and using a knockdown human NK cell line, we determined that ELF4 is necessary for normal NK cell development, terminal maturation, and function. Through characterization of the NK cells of the proband, expression of the proband\u27s variant in Elf4-/- mouse hematopoietic precursor cells, and a human in vitro NK cell maturation model, we established this ELF4 variant as a potentially novel cause of NKD

Clinical Characteristics and Outcomes of Posttransplant Lymphoproliferative Disorders Following Allogeneic Hematopoietic Stem Cell Transplantation in Korea

Between 1995 and 2003, seven cases of posttransplant lymphoproliferative disorder (PTLD) were identified among 1,116 patients who received allogeneic hematopoietic stem cell transplantations (HSCT) at Catholic HSCT Center (overall incidence 0.6%). Five (71.4%) patients had episodes of acute graft-versus-host-disease (GVHD) and were treated with steroids. Cervical lymphadenopathy was observed in most cases (71.4%), but clinical symptoms varied depending on the involved sites. Pathologic findings varied: 1 case of plasmacytic hyperplasia, 3 of polymorphic PTLD, 2 of diffuse large B-cell lymphoma, 1 of large T-cell lymphoma, which proved to be associated with Epstein-Barr virus (EBV). The proportion of EBV-negative PTLD was 33.3%. Five patients demonstrated a good response to treatment (treatment response rate 71.4%). The overall mortality was 42.8%, and one death was directly attributable to PTLD. The incidence of PTLD is expected to increase, based on the rising use of grafts from alternative donors and recent clinical features of PTLD manifested by a disseminated and fulminant nature. It is necessary to have a high level of suspicion when monitoring patients and readily adopt prompt and effective cellular immunotherapy for PTLD

The Cytosolic Protein G0S2 Maintains Quiescence in Hematopoietic Stem Cells

Bone marrow hematopoietic stem cells (HSCs) balance proliferation and differentiation by integrating complex transcriptional and post-translational mechanisms regulated by cell intrinsic and extrinsic factors. We found that transcripts of G0/G1 switch gene 2 (G0S2) are enriched in lineage− Sca-1+ c-kit+ (LSK) CD150+ CD48− CD41− cells, a population highly enriched for quiescent HSCs, whereas G0S2 expression is suppressed in dividing LSK CD150+ CD48− cells. Gain-of-function analyses using retroviral expression vectors in bone marrow cells showed that G0S2 localizes to the mitochondria, endoplasmic reticulum, and early endosomes in hematopoietic cells. Co-transplantation of bone marrow cells transduced with the control or G0S2 retrovirus led to increased chimerism of G0S2-overexpressing cells in femurs, although their contribution to the blood was reduced. This finding was correlated with increased quiescence in G0S2-overexpressing HSCs (LSK CD150+ CD48−) and progenitor cells (LS−K). Conversely, silencing of endogenous G0S2 expression in bone marrow cells increased blood chimerism upon transplantation and promoted HSC cell division, supporting an inhibitory role for G0S2 in HSC proliferation. A proteomic study revealed that the hydrophobic domain of G0S2 interacts with a domain of nucleolin that is rich in arginine-glycine-glycine repeats, which results in the retention of nucleolin in the cytosol. We showed that this cytosolic retention of nucleolin occurs in resting, but not proliferating, wild-type LSK CD150+ CD48− cells. Collectively, we propose a novel model of HSC quiescence in which elevated G0S2 expression can sequester nucleolin in the cytosol, precluding its pro-proliferation functions in the nucleolus

DYRK2 controls a key regulatory network in chronic myeloid leukemia stem cells

Leukemia: Wiping out hidden reservoirs of stem cells A master regulator protein may represent a key vulnerability for the eradication of stem cell populations that drive recurrence in chronic myeloid leukemia (CML). These leukemia stem cells (LSCs) remain robust and proliferative even after treatment has wiped out other reservoirs of cancer. Chun Shik Park and Daniel Lacorazza at Baylor College of Medicine, Texas Children’s Hospital, Houston, Texas, USA, have reviewed current knowledge about the molecular mechanisms that promote LSC survival, focusing on a protein called DYRK2. This protein’s normal physiological function is poorly understood, but it appears to restrain the uncontrolled proliferation of LSCs. Reduced expression of DYRK2 in these cells may play a major role in unleashing their tumorigenic potential. Agents that transiently reactivate DYRK2 could therefore prove a valuable adjunct to therapy, by promoting the deterioration and death of these cancer stem cells