A theoretical analysis of chemical exchange saturation transfer echo planar imaging (CEST‐EPI) steady state solution and the CEST sensitivity efficiency‐based optimization approach

Chemical exchange saturation transfer (CEST) MRI is sensitive to dilute labile protons and microenvironmental properties, augmenting routine relaxation‐based MRI. Recent developments of quantitative CEST (qCEST) analysis such as omega plots and RF‐power based ratiometric calculation have extended our ability to elucidate the underlying CEST system beyond the simplistic apparent CEST measurement. CEST MRI strongly varies with experimental factors, including the RF irradiation level and duration as well as repetition time and flip angle. In addition, the CEST MRI effect is typically small, and experimental optimization strategies have to be carefully evaluated in order to enhance the CEST imaging sensitivity. Although routine CEST MRI has been optimized largely based on maximizing the magnitude of the CEST effect, the CEST signal‐to‐noise (SNR) efficiency provides a more suitable optimization index, particularly when the scan time is constrained. Herein, we derive an analytical solution of the CEST effect that takes into account key experimental parameters including repetition time, imaging flip angle and RF irradiation level, and solve its SNR efficiency. The solution expedites CEST imaging sensitivity calculation, substantially faster than the Bloch–McConnell equation‐based numerical simulation approach. In addition, the analytical solution‐based SNR formula enables the exhaustive optimization of CEST MRI, which simultaneously predicts multiple optimal parameters such as repetition time, flip angle and RF saturation level based on the chemical shift and exchange rate. The sensitivity efficiency‐based optimization approach could simplify and guide imaging of CEST agents, including glycogen, glucose, creatine, gamma‐aminobutyric acid and glutamate. Copyright © 2016 John Wiley & Sons, Ltd.     

Hematopoietic stem cell therapy for malignant diseases

Allogeneic bone marrow or blood stem cell transplantation (SCT) has changed its face in the last two decades. The introduction of nonmyeloablative conditioning regimens has reduced procedure toxicity and allowed the application of SCT in patients and conditions in which SCT was not offered in the past. In this review we will summarize the changes and accomplishments achieved in the past years in the field of stem cell transplantation for malignant disorders.     

(E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU)

(E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU, Brivudin, Zostex, Zerpex, Zonavir), now more than 20 years after its discovery, still stands out as a highly potent and selective inhibitor of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) infections. It has been used in the topical treatment of herpetic keratitis and recurrent herpes labialis and the systemic (oral) treatment of herpes zoster (zona, shingles). The high selectivity of BVDU towards HSV-1 and VZV depends primarily on a specific phosphorylation of BVDU to its 5'-diphosphate (DP) by the virus-encoded thymidine kinase (TK). After further phosphorylation (by cellular enzymes), to the 5'-triphosphate (TP), the compound interferes as a competitive inhibitor/alternate substrate with the viral DNA polymerase. The specific phosphorylation by the HSV- and VZV-induced TK also explains the marked cytostatic activity of BVDU against tumor cells that have been transduced by the viral TK genes. This finding offers considerable potential in a combined gene therapy/chemotherapy approach for cancer. To the extent that BVDU or its analogues (i.e., BVaraU) are degraded (by thymidine phosphorylase) to (E)-5-(2-bromovinyl)uracil (BVU), they may potentiate the anticancer potency, as well as toxicity, of 5-fluorouracil. This ensues from the direct inactivating effect of BVU on dihydropyrimidine dehydrogenase, the enzyme that initiates the degradative pathway of 5-fluorouracil. The prime determinant in the unique behavior of BVDU is its (E)-5-(2-bromovinyl) substituent. Numerous BVDU analogues have been described that, when equipped with this particular pharmacophore, demonstrate an activity spectrum characteristic of BVDU, including selective anti-VZV activity.     

Ornithine Aminotransferase versus GABA Aminotransferase: Implications for the Design of New Anticancer Drugs

Ornithine aminotransferase (OAT) and γ‐aminobutyric acid aminotransferase (GABA‐AT) are classified under the same evolutionary subgroup and share a large portion of structural, functional, and mechanistic features. Therefore, it is not surprising that many molecules that bind to GABA‐AT also bind well to OAT. Unlike GABA‐AT, OAT had not been viewed as a potential therapeutic target until recently; consequently, the number of therapeutically viable molecules that target OAT is very limited. In this review the two enzymes are compared with respect to their active‐site structures, catalytic and inactivation mechanisms, and selective inhibitors. Insight is offered that could aid in the design and development of new selective inhibitors of OAT for the treatment of cancer.     

Novel rapid immunochromatographic test based on an enzyme immunoassay for detecting nucleocapsid antigen in SARS-associated coronavirus

A novel severe acute respiratory syndrome-associated coronavirus (SARS-CoV) has been discovered. The detection of both antigens and antibodies in SARS-CoV from human specimens with suspected SARS plays an important role in preventing infection. We developed a novel rapid immunochromatographic test (RICT) based on the sandwich format enzyme immunoassay (EIA) with an all-in-one device for detecting the native nucleocapsid antigen (N-Ag) of SARS-CoV using monoclonal antibodies (MoAbs), which we produced by immunizing recombinant N-Ag to mice. RICT is a qualitative assay for respiratory aspirates and serum specimens. With this assay, a positive result can be judged subjectively by the appearance of a blue line on the device 15 min after the sample is applied. RICT with several pairs of MoAbs showed a high sensitivity for the detection of recombinant N-Ag as well as viral N-Ag of SARS-CoV. rSN122 and rSN21-2 were the best MoAbs for immobilized antibody and enzyme labeling, respectively. With regard to analytical sensitivity, RICT detected N-Ag at 31 pg/mL for recombinant N-Ag, and at 1.99 x 10(2) TCID(50)/mL for SARS-CoV. The specificity of RICT was 100% when 150 human sera and 50 nasopharyngeal aspirates (NSPs) were used. RICT based on an EIA using the rSN122/rSN21-2 pair is a sensitive, specific, and reliable rapid assay for detecting N-Ag in SARS-CoV treated with either heat or Triton X-100.     

Predictive value of the serum level of N-terminal pro-brain natriuretic peptide and high-sensitivity C-reactive protein in left ventricular remodeling after acute myocardial infarction

This study was designed to measure the correlation between left ventricular (LV) remodeling 3 months after successful reperfusion therapy, and the levels of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) and high-sensitivity C-reactive protein (hs-CRP) at 3 days after acute myocardial infarction (AMI), and to determine the predictive levels of NT-proBNP and hs-CRP for LV remodeling. A total of 106 patients with first AMI were included in this study. Each patient was examined by echocardiography (ECG) on the third day and third month after AMI, and LV remodeling was determined by the difference in the LEV end-diastolic volume (LVEDV) between the third day and the third month. Serum NT-proBNP and hs-CRP level were measured 3 days after AMI. Then the correlation between the 3-months change in LVEDV and the levels of serum NT-proBNP or hs-CRP was determined. In addition, sensitivity and specificity were calculated with a receiver operating characteristic (ROC) curve to identify correspondence with LV remodeling (defined as the change rate of LVEDV >20%). Our results showed that the correlation coefficients with the change of LVEDV were 0.706 for serum NT-pro BNP (P<0.001) and 0.596 for hs-CRP (P<0.05). With a cutoff value of 0.2, the area under the ROC curve (AUC) was 0.894 for NT-proBNP and 0.825 for hs-CRP. Although the AUC did not statistically differ between NT-proBNP and hs-CRP, NT-proBNP is more effective than serum hs-CRP as a marker to predict LV remodeling.     

Extracorporeal photopheresis in pediatric patients: Practical and technical considerations

In adults, extracorporeal photopheresis (ECP) is widely utilized for a variety of indications, most commonly cutaneous T‐cell lymphoma, acute or chronic graft‐versus‐host disease (GVHD), solid organ transplant rejection, and other autoimmune and T‐cell‐mediated disorders. In pediatric patients, the majority of case series and reports have focused on its use in the management of acute and chronic GVHD. Currently utilized ECP technologies were designed for adult patients and there are several challenges in adapting these technologies for use in children. In our review, we focus on practical considerations and procedural modifications for ECP use in pediatric patients, with special attention to patient safety.     

Interleukin‐18 gene 105A/C genetic polymorphism is associated with the susceptibility of Kawasaki disease

Interleukin‐18 (IL‐18)‐656T/G, ‐607A/C, and ‐137C/G promoter polymorphisms had been reported associated with Kawasaki disease (KD). An IL‐18 genetic A/C polymorphism at coding position 105 (rs549908) has been linked with asthma, rheumatoid, and systemic lupus erythematosus. We tested a hypothesis that the IL‐18 105A/C genetic polymorphism confers KD susceptibility. Study participants were Taiwanese KD patients and a healthy control group. Our data indicated that the frequency of C allele was significantly higher in the patient group (13.9%) than in the control group (2.7%; P<0.0001, odds ratio [OR]=5.93; 95% confidence interval [CI]=2.57–13.73). Therefore, persons with the C allele may have higher risk of deve loping KD. In addition, compared with the haplotype frequencies between case and control groups, the KD patients with TACC haplotype appeared to be a significant “at‐risk” haplotype compared with other haplotypes (OR: 4.62, 95% CI: 1.71–12.43; P=0.001). KD patient with the TAGA haplotype appeared to be a significant “protective” haplotype compared with other haplotypes (OR: 0.51, 95% CI:0.29–0.89; P=0.017). Our results suggest that 105A/C polymorphism and the haplotypes in IL‐18 gene are associated with the risk of KD in Taiwanese population. Clin. Lab. Anal. 23:71–76, 2009. © 2009 Wiley‐Liss, Inc.     

Surface functionalization of superparamagnetic nanoparticles for the development of highly efficient magnetic resonance probe for macrophages

In vivo magnetic resonance imaging (MRI) tracking of macrophages plays an important role in monitoring and understanding numerous human diseases with high macrophage activity. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) of ～12 nm were surface‐functionalized with poly(DL ‐lactic acid‐co‐malic acid) copolymer (PLMA) via a nanoprecipitation method. The r₁, r₂ and r₂/r₁ values of the PLMA‐SPIONs obtained at a magnetic field of 3 T were 0.38, 196 and 516 mM ^?1 s^?1, respectively. The high r₂/r₁ ratio can be expected to provide enhanced MR contrast. The PLMA‐SPIONs were readily taken in by macrophages and the high iron uptake was confirmed via Prussian Blue staining and quantified by inductively coupled plasma mass spectrometry (ICP‐MS). No significant cytotoxicity was found even at a high nanoparticle loading of 67.7 pg Fe per cell. A linear relationship between R₂ and R values and the number of PLMA‐SPIONs labeled cells was observed in vitro. As a result of the significantly higher R than R₂ effects, an in vitro detection threshold of about 2820 labeled cells was achieved with short labeling time and low nanoparticle concentration using a clinical 3 T MRI scanner. Thus, the PLMA‐SPIONs can be potentially useful as magnetic resonance probes for targeting and tracking macrophages. Copyright © 2011 John Wiley & Sons, Ltd.     

IL-2 gene C/T polymorphism is associated with prostate cancer

Cytokines are reported to be associated with the formation of prostate cancer. Our aim was to investigate whether C/T polymorphisms of the interleukin-2 (IL-2) gene and IL-2 receptor beta (IL-2RB) gene are associated with prostate cancer. We compared the frequency of the polymorphisms of the IL-2 gene and the IL-2RB gene between 96 patients with prostate cancer and 105 healthy male volunteers from the same area (age >60 years). They were followed for at least 5 years. There was a significant difference in distribution of the genotype of the IL-2 gene polymorphism between the prostate cancer group and the control group (P = 0.017). The distribution of the TT homozygote of the IL-2 gene was significantly higher in the cancer group (32.3%) than in the control group (16.2%). However, no significant statistical difference was found between the polymorphism of the IL-2 gene and prostate cancer in survival analysis during a 5-year follow up period (log rank test; P = 0.19). There was no significant difference in the distribution of the genotype of the IL-2RB gene polymorphism between controls and cancer patients (P = 0.388). This study suggests that the IL-2 gene may be associated with susceptibility to prostate cancer in the Taiwan population.     

Significance of donor‐derived isoagglutinins in ABO‐Incompatible hematopoietic stem cell transplantation

Changes in isoagglutinin titers may have implications in the occurrence of hematological complications such as pure red cell aplasia or immune‐mediated hemolysis. Furthermore, isoagglutinin titers could reflect immunohematological reconstitution after transplantation. The objective of this study was to examine the relationship between donor‐derived isoagglutinins (DDIs) and graft‐versus‐host disease (GVHD). In total, 114 patients who underwent ABO‐incompatible allogeneic hematopoietic stem cell transplantation (HSCT) were analyzed. Among these patients, 27.7% demonstrated increased donor‐derived isoagglutinins (IDDIs) against red blood cells (RBCs) of the recipient, and 32.8% of the patients showed DDIs that were not against RBCs of the recipient. Patients with acute GVHD and DDIs against RBCs of the recipient tended to have higher incidences of IDDIs that occurred before posttransplant day 60 compared with patients without acute GVHD (17.3 vs. 3.9%, P=0.058). In patients with acute GVHD, IDDIs occurred significantly earlier (mean, day 32 vs. 181, P=0.046), the period of elevation was shorter (mean, day 36 vs. 134, P=0.033), and the donors were younger (mean, 28 vs. 36 years, P=0.01) than those without GVHD. Moreover, significant correlations were found between IDDIs and acute GVHD. Taken together, these data underscore a possible role for humoral immunity in GVHD after HSCT. J. Clin. Lab. Anal. 22:383–390, 2008. © 2008 Wiley‐Liss, Inc.     

Development of anaplastic lymphoma kinase (ALK) small-molecule inhibitors for cancer therapy

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase (RTK) involved in the genesis of several human cancers; indeed, ALK was initially identified in constitutively activated and oncogenic fusion forms--the most common being nucleophosmin (NPM)-ALK--in a non-Hodgkin's lymphoma (NHL) known as anaplastic large-cell lymphoma (ALCL) and subsequent studies identified ALK fusions in the human sarcomas called inflammatory myofibroblastic tumors (IMTs). In addition, two recent reports have suggested that the ALK fusion, TPM4-ALK, may be involved in the genesis of a subset of esophageal squamous cell carcinomas. While the cause-effect relationship between ALK fusions and malignancies such as ALCL and IMT is very well established, more circumstantial links implicate the involvement of the full-length, normal ALK receptor in the genesis of additional malignancies including glioblastoma, neuroblastoma, breast cancer, and others; in these instances, ALK is believed to foster tumorigenesis following activation by autocrine and/or paracrine growth loops involving the reported ALK ligands, pleiotrophin (PTN) and midkine (MK). There are no currently available ALK small-molecule inhibitors approved for clinical cancer therapy; however, recognition of the variety of malignancies in which ALK may play a causative role has recently begun to prompt developmental efforts in this area. This review provides a succinct summary of normal ALK biology, the confirmed and putative roles of ALK fusions and the full-length ALK receptor in the development of human cancers, and efforts to target ALK using small-molecule kinase inhibitors.     

Effective expansion of human adipose‐derived stromal cells and bone marrow‐derived mesenchymal stem cells cultured on a fragmin/protamine nanoparticles‐coated substratum with human platelet‐rich plasma

Fragmin/protamine nanoparticles (F/P NPs) can be stably coated onto plastic surfaces and used as a substratum for the absorption and controlled release of growth factors (GFs) secreted from human platelet‐rich plasma (PRP). In this study, we investigated the capability of F/P NP‐coated plates to act as a substratum for the proliferation of human adipose‐derived stromal cells (ASCs) and bone marrow‐derived mesenchymal stem cells (BMSCs) with GFs in PRP. Both cell types adhered well to the F/P NP‐coated plates and grew optimally, with a doubling time of 30 and 32 h in low‐concentration PRP (0.5%) medium supplemented with 5 ng/ml fibroblast growth factor‐2 (FGF‐2) on the F/P NP‐coated plates. These cells maintained their multilineage potential for differentiation into adipocytes or osteoblasts. Furthermore, ASCs and BMSCs grew well in medium without PRP and FGF‐2 on F/P NP‐coated plates pretreated with PRP and FGF‐2 in a concentration‐dependent manner. Thus, F/P NP‐coated plates are a useful substratum for the adherence and proliferation of ASCs and BMSCs in low‐concentration PRP medium supplemented with FGF‐2. No xenogeneic serum is required. Copyright © 2012 John Wiley & Sons, Ltd.