ß-eye: A benchtop system for in vivo molecular screening of labeled compounds.

Preclinical nuclear molecular imaging speeds up the mean time from synthesis to market, in drug development process. Commercial imaging systems have in general high cost, require high-cost service contracts, special facilities and trained staff. In the current work, we present ß-eye, a benchtop system for in vivo molecular screening of labeled compounds with Positron Emission Tomography (PET) isotopes. The developed system is based on a dual-head geometry, offering simplicity and decreased cost. The goal of the design is to provide 2D, real-time radionuclide images of mice, allowing the recording of fast frames and thus perform fast kinetic studies, with spatial resolution of ∼2 mm. Performance evaluation demonstrates the ability of ß-eye to provide quantitative results for injected activities lower than 1.5 MBq, which is adequate for pharmacodynamic studies in small mice.

The Impact of Positron Range on PET Resolution, Evaluated with Phantoms and PHITS Monte Carlo Simulations for Conventional and Non-conventional Radionuclides.

PURPOSE: The increasing interest and availability of non-standard positron-emitting radionuclides has heightened the relevance of radionuclide choice in the development and optimization of new positron emission tomography (PET) imaging procedures, both in preclinical research and clinical practice. Differences in achievable resolution arising from positron range can largely influence application suitability of each radionuclide, especially in small-ring preclinical PET where system blurring factors due to annihilation photon acollinearity and detector geometry are less significant. Some resolution degradation can be mitigated with appropriate range corrections implemented during image reconstruction, the quality of which is contingent on an accurate characterization of positron range. PROCEDURES: To address this need, we have characterized the positron range of several standard and non-standard PET radionuclides (As-72, F-18, Ga-68, Mn-52, Y-86, and Zr-89) through imaging of small-animal quality control phantoms on a benchmark preclinical PET scanner. Further, the Particle and Heavy Ion Transport code System (PHITS v3.02) code was utilized for Monte Carlo modeling of positron range-dependent blurring effects. RESULTS: Positron range kernels for each radionuclide were derived from simulation of point sources in ICRP reference tissues. PET resolution and quantitative accuracy afforded by various radionuclides in practicable imaging scenarios were characterized using a convolution-based method based on positron annihilation distributions obtained from PHITS. Our imaging and simulation results demonstrate the degradation of small animal PET resolution, and quantitative accuracy correlates with increasing positron energy; however, for a specific "benchmark" preclinical PET scanner and reconstruction workflow, these differences were observed to be minimal given radionuclides with average positron energies below ~ 400 keV. CONCLUSION: Our measurements and simulations of the influence of positron range on PET resolution compare well with previous efforts documented in the literature and provide new data for several radionuclides in increasing clinical and preclinical use. The results will support current and future improvements in methods for positron range corrections in PET imaging.

Production cross-sections of 181-186Re isotopes from proton bombardment of natural tungsten.

Cross-sections for the production of (181)Re, (182m)Re, (182g)Re, (183)Re, (184)Re, and (186)Re from proton bombardment of natural tungsten have been measured using the stacked foil technique for proton energies up to 17.6 MeV. Results are compared with the theoretical excitation functions as calculated by the EMPIRE II code (version 2.19) and experimental literature values. Results are in strong agreement with some of the previously reported literature as well at theoretical calculations for multiple reactions providing for more reliable estimates for the (186)W(p,n)(186)Re reaction.

Microgeographic variation of HLA-A, -B, and -DR haplotype frequencies in Tuscany, Italy: implications for recruitment of bone marrow donors.

HLA-A/B haplotype frequencies were estimated in a sample of 2355 bone marrow donors born in a subregion of Tuscany (Italy), and the HLA-A, -B, -DR haplotype frequencies were estimated in a subset of 809 individuals. This area was divided in 10 subsamples (two-locus haplotypes), or six subsamples (three-locus haplotypes), all with sample size >50, based on administrative boundaries. A considerable level of heterogeneity of haplotype frequency was present among subsamples; this heterogeneity was associated to a large variation (up to 4-fold) of the number of new donors that must be typed in order to reach 50% chance of finding an HLA-A, -B phenotype of intermediate frequency. Knowledge of the genetic structure of the population at a microgeographic level may be useful in directing the search of specific bone marrow donors.

Identification of a novel HLA-DPB1 allele, DPB1*9701, by sequence-based typing.

This report describes the identification of a novel DPB1 allele, DPB *9701, found in an Italian Caucasian individual. The new allele was detected by human leukocyte antigen sequence-based typing carried out to investigate the role of genetic factors in determining the outcome of hepatitis C virus infection. DPB1*9701 was identical to DPB1*0501 except for a single-nucleotide substitution at codon 43 (GGG --> TGG). This nucleotide change is a non-synonymous mutation and results in the amino acid substitution glycine (G) --> tryptophan (W). The nucleotide sequence has been deposited in GenBank under the accession number AY033075, and denominated DPB1*9701 by the official World Health Organization Nomenclature Committee.

HLA-DR in couples associated with preeclampsia: background and updating by DNA sequencing.

The placenta acts as an immunological barrier between the mother and the fetal "graft", allowing two antigenically different organisms to tolerate one another. In placentae from preeclamptic women, we have demonstrated, by an ultrastructural assessment and an immunohistochemical study, a placental barrier breakage leading to the mixing of maternal and fetal antigenically different blood. This condition could be responsible for the triggering of a maternal rejection reaction that we presume to be at the basis of the preeclamptic syndrome. Thus, we have investigated the Human Leukocyte class II DR antigens (HLA-DR), whose role in self and non-self recognition is well known, in women with preeclampsia, their partners and in control couples using the serological Terasaki tecnique. The results showed a statistically significant increase of HLA-DR homozygosity and a reduced antigenic variety in the preeclamptic women and their partners with respect to controls. In this update, we have examined the 2nd exon of the human gene, HLA-DRB1, on the short arm of the chromosome 6 using DNA sequence-based typing (S-BT) PCR in 56 preeclamptic couples and 64 control couples. The results have confirmed the significant excess of HLA-DR homozygosity in couples associated with preeclampsia versus controls. From our results, it emerges that HLA-DR homozygosity and the reduced antigenic variety seem to be associated to a major risk for preeclampsia, which further appears to be a "couple's disease".

Correlations of Y chromosome microchimerism with disease activity in patients with SLE: analysis of preliminary data.

BACKGROUND: Recently it has been suggested that microchimerism may have a significant role in the aetiopathogenesis of some autoimmune diseases. OBJECTIVES: To evaluate the incidence of microchimerism in systemic lupus erythematosus (SLE), to quantify the phenomenon, to evaluate changes of microchimerism during follow up, and to correlate these data with clinical and laboratory variables. METHODS: Patients were selected for the study on the basis of the following criteria: (a) pregnancy with at least one male offspring; (b) no history of abortion and blood transfusion. Microchimerism was detected using a competitive nested polymerase chain reaction for a specific Y chromosome sequence and an internal competitor designed ad hoc. Disease activity and organ involvement were also evaluated. RESULTS: Sixty samples from 22 patients with SLE and 24 healthy controls were examined. Microchimerism was seen in 11 (50%) patients and 12 (50%) controls. The mean number of male equivalent cells was 2.4 cells/100 000 (range 0.1-17) in patients with SLE and 2.5 (range 0.2-1.8) in healthy controls. No differences in the incidence of microchimerism or in the number of microchimeric cells were found between patients and healthy controls. Patients with a history of lupus nephritis had a higher mean number of fetal cells than patients with no such history. Disease activity did not appear to correlate with microchimerism. CONCLUSIONS: The preliminary data suggest that microchimerism does not interfere with the disease course of SLE, although further analysis on larger groups will be necessary to confirm these observations.

Identification of a novel HLA-DPB1 allele, DPB1*02014, by sequence-based typing.

In this report we describe the identification of a novel DPB1 allele, DPB1*02014, found in an Italian Caucasian individual. The new allele was detected during routine HLA sequence-based typing (SBT) for an individual undergoing bone marrow transplantation. DPB1*02014 was identical to DPB1*02012 except for a single nucleotide substitution in codon 72 (GTG-->GTT). This nucleotide change represents a synonimous mutation, as both triplets code for a valine. This new allele has been submitted to GenBank and assigned the accession number AF326565. The WHO Nomenclature Committee has officially assigned the name DPB1*02014.

A protein tyrosine phosphatase activity associated with the hepatocyte growth factor/scatter factor receptor.

The receptor for the growth and motility factor, hepatocyte growth factor/scatter factor (HGF/SF), is a transmembrane tyrosine kinase encoded by the MET oncogene. Previous work has shown that receptor phosphorylation on tyrosine is critical for both kinase activation and association with intracellular signal transducers. In this paper, we report that a protein tyrosine phosphatase activity (PTP) coprecipitates with the HGF/SF receptor. The associated PTP activity correlates with the kinase activation of the receptor, increasing up to 5-fold over the basal level after HGF/SF stimulation. The increase is reversible and time- and dose-dependent. A comparable level of activity is associated with constitutively tyrosine-phosphorylated receptors immunoprecipitated from cells where the MET oncogene is amplified and overexpressed. In these cells, a parallel decrease in PTP activity is observed after inhibition of receptor tyrosine phosphorylation following protein kinase C activation. The associated PTP activity is effective in dephosphorylating the HGF/SF receptor. These data show that a protein tyrosine phosphatase is functionally coupled to the HGF/SF receptor.