Lead-free MCP to improve coincidence time resolution and reduce MCP direct interactions.

Achieving direct imaging of the annihilation position of a positron on an event-by-event basis using an ultrafast detector would have a great impact on the field of nuclear medicine. Cherenkov emission is the most attractive physical phenomenon for realizing such an ultrafast timing performance. Moreover, a microchannel-plate photomultiplier tube (MCP-PMT) is one of the most promising photodetectors for fully exploiting the fast timing properties of Cherenkov emission owing to its excellent single photon time resolution of 25 ps full width at half maximum (FWHM). However, as the MCP structure generally contains a lead compound, the gamma rays frequently and directly interact with the MCP, resulting in the degradation of its timing performance and generation of undesirable side peaks in its coincidence timing histogram. To overcome this problem, we have developed a new MCP-PMT based on an MCP consisting of borosilicate glass, thus drastically reducing the probability of the photoelectric effect occurring in the MCP. To evaluate its insensitivity to gamma rays and its timing performance, a coincidence experiment was performed and showed that the probability of direct interactions was reduced by a factor of 3.4. Moreover, a coincidence time resolution of 35.4 ± 0.4 ps FWHM, which is equivalent to a position resolution of 5.31 mm, was obtained without any pulse height/area cut, improving to 28.7 ± 3.0 ps when selecting on the highest amplitude events by careful optimization of the voltage divider circuit of the new MCP-PMT. The timing performance of this new MCP-PMT presents an important step toward making direct imaging possible.

Application of bead array technology to simultaneous detection of human leucocyte antigen and human platelet antigen antibodies.

BACKGROUND: Detection of antibodies against human leucocyte antigens (HLA) and human platelet antigens (HPA) is crucial for patients refractory to platelet transfusion therapy. However, a reliable and high-throughput method for HLA cross-matching and detecting HPA antibodies has not yet been described. STUDY DESIGN AND METHODS: Immunocomplex capture fluorescence analysis (ICFA) was developed for high-throughput, simultaneous detection of HLA and HPA antibodies. Microarray beads were separately coupled with monoclonal antibodies specific for CD36, CD41, CD42b, CD49b, CD61 and HLA class I antigens. Platelets reacting with patient serum were lysed and the lysates were incubated with the bead mixture to specifically capture antigen-antibody complexes via the epitopes on platelet glycoproteins or HLA antigens. The beads capturing immunocomplexes were then subjected to flow cytometric analysis. RESULTS: Immunocomplex capture fluorescence analysis was validated using 50 serum samples containing HLA antibodies and 20 serum samples containing HPA antibodies. The method enabled the detection of all the HLA antibodies with a sensitivity comparable to that of the purified HLA antigen-coated pooled-bead assay (FlowPRA, One Lambda, Canoga Park, CA, USA). The method also enabled the detection of all the HPA antibodies with a sensitivity higher than that of the mixed passive haemagglutination. CONCLUSION: In this study, we developed a rapid, simple and reliable method for the simultaneous analysis of HLA and HPA antibodies. ICFA can also be used as an alternative to the lymphocyte cytotoxicity test for HLA cross-matching.

JAK/STAT pathway inhibition overcomes IL7-induced glucocorticoid resistance in a subset of human T-cell acute lymphoblastic leukemias.

While outcomes for children with T-cell acute lymphoblastic leukemia (T-ALL) have improved dramatically, survival rates for patients with relapsed/refractory disease remain dismal. Prior studies indicate that glucocorticoid (GC) resistance is more common than resistance to other chemotherapies at relapse. In addition, failure to clear peripheral blasts during a prednisone prophase correlates with an elevated risk of relapse in newly diagnosed patients. Here we show that intrinsic GC resistance is present at diagnosis in early thymic precursor (ETP) T-ALLs as well as in a subset of non-ETP T-ALLs. GC-resistant non-ETP T-ALLs are characterized by strong induction of JAK/STAT signaling in response to interleukin-7 (IL7) stimulation. Removing IL7 or inhibiting JAK/STAT signaling sensitizes these T-ALLs, and a subset of ETP T-ALLs, to GCs. The combination of the GC dexamethasone and the JAK1/2 inhibitor ruxolitinib altered the balance between pro- and anti-apoptotic factors in samples with IL7-dependent GC resistance, but not in samples with IL7-independent GC resistance. Together, these data suggest that the addition of ruxolitinib or other inhibitors of IL7 receptor/JAK/STAT signaling may enhance the efficacy of GCs in a biologically defined subset of T-ALL.

Existence of multiple receptors in single neurons: responses of single bullfrog olfactory neurons to many cAMP-dependent and independent odorants.

The responses of single bullfrog olfactory neurons to various odorants were measured with the whole-cell patch clamp which offers direct information on cellular events and with the ciliary recording technique to obtain stable quantitative data from many neurons. A large portion of single olfactory neurons (about 64% and 79% in the whole-cell recording and in the ciliary recording, respectively) responded to many odorants with quite diverse molecular structures, including both odorants previously indicated to be cAMP-dependent (increasing) and independent odorants. One odorant elicited a response in many cells; e.g. hedione and citralva elicited the response in 100% and 92% of total neurons examined with the ciliary recording technique. To confirm that a single neuron carries different receptors or transduction pathways, the cross-adaptation technique was applied to single neurons. Application of hedione to a single neuron after desensitization of the current in response to lyral or citralva induced an inward current with a similar magnitude to that applied alone. It was suggested that most single olfactory neurons carry multiple receptors and at least dual transduction pathways.

Evaluation of Uniform-Sized Microcapsules Using a Vibration-Nozzle Method.

In order to prepare microcapsules (MC) using polyvinylacetal diethyl-aminoacetate (AEA) gel, we have studied both the unique properties of AEA gel, in which cold-water solution forms a hard gel with exclusion of water at high temperature, and the microencapsulation technique for clarithromycin (CAM), which has an unpleasant taste (1, 2). In our previous paper (3), we described a new uniform-sized microencapsulation machine with a vibration nozzle with 536 holes 100µ in diameter designed for precise regulation of dissolution of CAM from MC.In order to evaluate the MC thus obtained, we prepared syrups (without water) by adding sweetening agents to MC, and conducted a dissolution test at various pHs using the method described in the Japanese Pharmacopoeia (12th edition), a test for bitter taste and a test to determine bioavailability (BA) in human subjects. At pHs below 4.0,100% of CAM in MC was dissolved from the syrup within 5min. However, there was little dissolution of CAM from syrup at pH6.8. The results of the test for bitter taste showed that the syrup preparations, which were administered to 12 male and female volunteers with 20ml water, masked bitter taste completely during the 60min period following administration of the syrup. The mean area under the serum concentration-time curve (AUCo-24) and the maximum serum concentration (Cmax) for administration of syrup preparations to 6 male volunteers were 5.66 ± 0.73µg·hr/ml and 0.66 ± 0.13µg/ml, respectively. Blood concentration was maintained at a level above the minimum inhibitory concentration for gram-positive bacteria for a period of about 14hr after administration, demonstrating the usefulness of the syrup preparation.

Penetration of imipenem and other antibiotics into inflammatory exudate and their efficacy in pseudomonas infection in the rat granuloma pouch model.

The rat granuloma pouch model was used to study the penetration of imipenem into inflammatory exudate and its efficacy in an experimental local infection. Rats were given a single intravenous injection of drug via the tail vein at a dose of 40 mg/kg. The peak concentrations of imipenem, ceftizoxime, cefazolin, and cefsulodin in exudates ranged from 10.1 to 12.3 mg/l, except that ampicillin achieved only 5.4 mg/l. Imipenem rapidly reached peak concentration after injection, but the half life for elimination of imipenem from exudate was 77.7 min, which was shorter than that of other beta-lactam antibiotics. Imipenem exhibited more rapid reduction in bacterial growth than cefsulodin in an experimental local infection with Pseudomonas aeruginosa in the pouch model. The results suggested that imipenem was an effective agent in treating the local infection.

Nucleotide sequence of a new Fc gamma receptor IIIB allele that codes for a neutrophil antigen.

A new allele of the human neutrophil antigen (HNA) system (tentatively called NA2M) was discovered and its nucleotide sequence was determined. NA2M differs in a single nucleotide (193G-->A) from FCGR3B*2(NA2), resulting in an amino acid change (54Glu-->Lys). The frequency of the NA2M gene in the Japanese population was estimated to be 0.008. Granulocytes of individuals possessing NA2M reacted with HNA-1b(NA2)-specific monoclonal antibody (TAG2) in the GIFT assay.